Unnamed: 0
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40.3k
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float64
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100
27,900
Given $x_1$ and $x_2$ are the two real roots of the quadratic equation in $x$: $x^2 - 2(m+2)x + m^2 = 0$. (1) When $m=0$, find the roots of the equation; (2) If $(x_1 - 2)(x_2 - 2) = 41$, find the value of $m$; (3) Given an isosceles triangle $ABC$ with one side length of 9, if $x_1$ and $x_2$ happen to be the lengths of the other two sides of $\triangle ABC$, find the perimeter of this triangle.
19
37.5
27,901
In $\triangle ABC$ , medians $\overline{AD}$ and $\overline{CE}$ intersect at $P$ , $PE=1.5$ , $PD=2$ , and $DE=2.5$ . What is the area of $AEDC?$ [asy] unitsize(75); pathpen = black; pointpen=black; pair A = MP("A", D((0,0)), dir(200)); pair B = MP("B", D((2,0)), dir(-20)); pair C = MP("C", D((1/2,1)), dir(100)); pair D = MP("D", D(midpoint(B--C)), dir(30)); pair E = MP("E", D(midpoint(A--B)), dir(-90)); pair P = MP("P", D(IP(A--D, C--E)), dir(150)*2.013); draw(A--B--C--cycle); draw(A--D--E--C); [/asy]
13.5
1.5625
27,902
Let $ABCDE$ be a convex pentagon such that: $\angle ABC=90,\angle BCD=135,\angle DEA=60$ and $AB=BC=CD=DE$ . Find angle $\angle DAE$ .
30
18.75
27,903
In response to the national policy of expanding domestic demand, a manufacturer plans to hold a promotional event at the beginning of 2015. After investigation and estimation, the annual sales volume (i.e., the annual production volume $x$ in ten thousand units) and the annual promotional expenses $t$ (where $t > 0$) in ten thousand yuan satisfy $x=4- \frac {k}{t}$ (where $k$ is a constant). If the annual promotional expenses $t$ are 1 ten thousand yuan, the annual sales volume of the product is 1 ten thousand units. It is known that the fixed investment for the product in 2015 is 60 thousand yuan, and an additional investment of 120 thousand yuan is required to produce 1 ten thousand units of the product. The manufacturer sets the selling price of each unit to 1.5 times the average cost of the product (the product cost includes both fixed and additional investments). - (Ⅰ) Express the profit $y$ (in ten thousand yuan) of the manufacturer for this product in 2015 as a function of the annual promotional expenses $t$ (in ten thousand yuan); - (Ⅱ) How much should the manufacturer invest in annual promotional expenses in 2015 to maximize profit?
3 \sqrt {2}
0
27,904
Let $\mathcal{T}$ be the set of real numbers that can be represented as repeating decimals of the form $0.\overline{abcd}$ where $a, b, c, d$ are distinct digits. Find the sum of the elements of $\mathcal{T}.$
2520
7.8125
27,905
Given a constant function on the interval $(0,1)$, $f(x)$, which satisfies: when $x \notin \mathbf{Q}$, $f(x)=0$; and when $x=\frac{p}{q}$ (with $p, q$ being integers, $(p, q)=1, 0<p<q$), $f(x)=\frac{p+1}{q}$. Determine the maximum value of $f(x)$ on the interval $\left(\frac{7}{8}, \frac{8}{9}\right)$.
$\frac{16}{17}$
0
27,906
Out of 1500 people surveyed, $25\%$ do not like television, and out of those who do not like television, $15\%$ also do not like books. How many people surveyed do not like both television and books?
56
96.875
27,907
In the expansion of $(2x +3y)^{20}$ , find the number of coefficients divisible by $144$ . *Proposed by Hannah Shen*
15
61.71875
27,908
What is the total number of digits used when the first 2500 positive even integers are written?
9448
34.375
27,909
Four people, A, B, C, and D, stand in a line from left to right and are numbered 1, 2, 3, and 4 respectively. They have the following conversation: A: Both people to my left and my right are taller than me. B: Both people to my left and my right are shorter than me. C: I am the tallest. D: There is no one to my right. If all four of them are honest, what is the 4-digit number formed by the sequence of their numbers?
2314
3.125
27,910
In a convex polygon with 1992 sides, the minimum number of interior angles that are not acute is:
1989
7.8125
27,911
A rigid board with a mass \( m \) and a length \( l = 20 \) meters partially lies on the edge of a horizontal surface, overhanging it by three quarters of its length. To prevent the board from falling, a stone with a mass of \( 2m \) was placed at its very edge. How far from the stone can a person with a mass of \( m / 2 \) walk on the board? Neglect the sizes of the stone and the person compared to the size of the board.
15
7.8125
27,912
Let \( n \) be the product of 3659893456789325678 and 342973489379256. Determine the number of digits of \( n \).
34
98.4375
27,913
In $\triangle ABC$, lines $CF$ and $AD$ are drawn such that $\dfrac{CD}{DB}=\dfrac{2}{3}$ and $\dfrac{AF}{FB}=\dfrac{1}{3}$. Let $s = \dfrac{CQ}{QF}$ where $Q$ is the intersection point of $CF$ and $AD$. Find $s$. [asy] size(8cm); pair A = (0, 0), B = (9, 0), C = (3, 6); pair D = (6, 4), F = (6, 0); pair Q = intersectionpoints(A--D, C--F)[0]; draw(A--B--C--cycle); draw(A--D); draw(C--F); label("$A$", A, SW); label("$B$", B, SE); label("$C$", C, N); label("$D$", D, NE); label("$F$", F, S); label("$Q$", Q, S); [/asy]
\frac{3}{5}
0
27,914
Given the ellipse $x^{2}+4y^{2}=16$, and the line $AB$ passes through point $P(2,-1)$ and intersects the ellipse at points $A$ and $B$. If the slope of line $AB$ is $\frac{1}{2}$, then the value of $|AB|$ is ______.
2\sqrt{5}
97.65625
27,915
Consider the set of points that are inside or within two units of a rectangular parallelepiped that measures 2 by 3 by 6 units. Calculate the total volume of this set, expressing your answer in the form $\frac{m+n\pi}{p}$, where $m$, $n$, and $p$ are positive integers with $n$ and $p$ being relatively prime.
\frac{540 + 164\pi}{3}
5.46875
27,916
There are five unmarked envelopes on a table, each containing a letter for a different person. If the mail is randomly distributed to these five people, with each person getting one letter, what is the probability that exactly three people receive the correct letter?
\frac{1}{12}
88.28125
27,917
Suppose the graph of \( y=g(x) \) includes the points \( (1,4), (2,6), \) and \( (3,2) \). Based only on this information, there are two points that must be on the graph of \( y=g(g(x)) \). If we call these points \( (a,b) \) and \( (c,d) \), what is \( ab + cd \)?
20
3.125
27,918
The non-negative difference between two numbers \(a\) and \(b\) is \(a-b\) or \(b-a\), whichever is greater than or equal to 0. For example, the non-negative difference between 24 and 64 is 40. In the sequence \(88, 24, 64, 40, 24, \ldots\), each number after the second is obtained by finding the non-negative difference between the previous 2 numbers. The sum of the first 100 numbers in this sequence is:
760
3.90625
27,919
An iterative average of the numbers 2, 3, 4, 6, and 7 is computed by arranging the numbers in some order. Find the difference between the largest and smallest possible values that can be obtained using this procedure.
\frac{11}{4}
0.78125
27,920
Given the expansion of $\left(x-\frac{a}{x}\right)^{5}$, find the maximum value among the coefficients in the expansion.
10
71.09375
27,921
Let $S_{n}$ be the sum of the first $n$ terms of an arithmetic sequence $\{a_{n}\}$ with distinct terms, given that $a_{3}a_{8}=3a_{11}$, $S_{3}=9$. 1. Find the general term formula for the sequence $\{a_{n}\}$. 2. If $b_{n}= \frac {1}{ \sqrt {a_{n}}+ \sqrt {a_{n+1}}}$, and the sum of the first $n$ terms of the sequence $\{b_{n}\}$ is $T_{n}$, find the minimum value of $\frac {a_{n+1}}{T_{n}}$.
4 \sqrt {2}
0
27,922
If $3 \in \{a, a^2 - 2a\}$, then the value of the real number $a$ is __________.
-1
3.90625
27,923
Consider the ellipse $C\_1$: $\frac{x^{2}}{2}+y^{2}=1$ and the ellipse $C\_2$: $\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1$ ($a > b > 0$). One focus of ellipse $C\_2$ has the coordinates $(\sqrt{5},0)$. The line $l$ with slope $1$ intersects ellipse $C\_2$ at points $A$ and $B$, and the midpoint $H$ of the line segment $AB$ has the coordinates $(2,-1)$. 1. Find the equation of ellipse $C\_2$. 2. Let $P$ be a point on the ellipse $C\_2$, and let $M$ and $N$ be points on the ellipse $C\_1$ such that $\overrightarrow{OP}=\overrightarrow{OM}+2\overrightarrow{ON}$. Determine whether the product of the slopes of lines $OM$ and $ON$ is constant. If it is, find the constant value; if not, explain the reason.
-\frac{1}{2}
60.15625
27,924
Let \( x \) and \( y \) be real numbers, \( y > x > 0 \), such that \[ \frac{x}{y} + \frac{y}{x} = 4. \] Find the value of \[ \frac{x + y}{x - y}. \]
\sqrt{3}
7.8125
27,925
Among the following four propositions: (1) The domain of the function $y=\tan (x+ \frac {π}{4})$ is $\{x|x\neq \frac {π}{4}+kπ,k\in Z\}$; (2) Given $\sin α= \frac {1}{2}$, and $α\in[0,2π]$, the set of values for $α$ is $\{\frac {π}{6}\}$; (3) The graph of the function $f(x)=\sin 2x+a\cos 2x$ is symmetric about the line $x=- \frac {π}{8}$, then the value of $a$ equals $(-1)$; (4) The minimum value of the function $y=\cos ^{2}x+\sin x$ is $(-1)$. Fill in the sequence number of the propositions you believe are correct on the line ___.
(1)(3)(4)
0
27,926
Given the digits $1$ through $7$ , one can form $7!=5040$ numbers by forming different permutations of the $7$ digits (for example, $1234567$ and $6321475$ are two such permutations). If the $5040$ numbers are then placed in ascending order, what is the $2013^{\text{th}}$ number?
3546127
0
27,927
Six chairs sit in a row. Six people randomly seat themselves in the chairs. Each person randomly chooses either to set their feet on the floor, to cross their legs to the right, or to cross their legs to the left. There is only a problem if two people sitting next to each other have the person on the right crossing their legs to the left and the person on the left crossing their legs to the right. The probability that this will **not** happen is given by $\frac{m}{n}$ where $m$ and $n$ are relatively prime positive integers. Find $m+n$ .
1106
1.5625
27,928
The spinner shown is divided into 6 sections of equal size. Determine the probability of landing on a section that contains the letter Q using this spinner.
\frac{2}{6}
0
27,929
1. Calculate the value of the following expression: $(1)(2\frac{7}{9})^{\frac{1}{2}} - (2\sqrt{3} - \pi)^{0} - (2\frac{10}{27})^{-\frac{2}{3}} + 0.25^{-\frac{3}{2}}$ 2. Given that $x + x^{-1} = 4 (0 < x < 1)$, find the value of ${x^{\frac{1}{2}}} + {x^{-\frac{1}{2}}}$.
\frac{389}{48}
0
27,930
Using the digits $0$, $1$, $2$, $3$, $4$ to form a four-digit number without repeating any digit, determine the total number of four-digit numbers less than $2340$.
40
10.9375
27,931
Please fold a long rope in half, then fold it in half again along the middle of the folded rope, and continue to fold it in half 5 times in total. Finally, cut the rope along the middle after it has been folded 5 times. At this point, the rope will be cut into ___ segments.
33
3.90625
27,932
Let \( ABC \) be a triangle such that \( AB = 2 \), \( CA = 3 \), and \( BC = 4 \). A semicircle with its diameter on \(\overline{BC}\) is tangent to \(\overline{AB}\) and \(\overline{AC}\). Compute the area of the semicircle.
\frac{27 \pi}{40}
3.125
27,933
Consider all possible quadratic polynomials $x^2 + px + q$ with a positive discriminant, where the coefficients $p$ and $q$ are integers divisible by 5. Find the largest natural number $n$ such that for any polynomial with the described properties, the sum of the hundredth powers of the roots is an integer divisible by $5^n$.
50
4.6875
27,934
A motorist left point A for point D, covering a distance of 100 km. The road from A to D passes through points B and C. At point B, the GPS indicated that 30 minutes of travel time remained, and the motorist immediately reduced speed by 10 km/h. At point C, the GPS indicated that 20 km of travel distance remained, and the motorist immediately reduced speed by another 10 km/h. (The GPS determines the remaining time based on the current speed of travel.) Determine the initial speed of the car if it is known that the journey from B to C took 5 minutes longer than the journey from C to D.
100
1.5625
27,935
Let $ABC$ be a right triangle with $m(\widehat{A})=90^\circ$ . Let $APQR$ be a square with area $9$ such that $P\in [AC]$ , $Q\in [BC]$ , $R\in [AB]$ . Let $KLMN$ be a square with area $8$ such that $N,K\in [BC]$ , $M\in [AB]$ , and $L\in [AC]$ . What is $|AB|+|AC|$ ?
12
13.28125
27,936
Calculate $(2.1)(50.5 + 0.15)$ after increasing $50.5$ by $5\%$. What is the product closest to?
112
10.15625
27,937
Find the number of ordered quintuples $(a,b,c,d,e)$ of nonnegative real numbers such that: \begin{align*} a^2 + b^2 + c^2 + d^2 + e^2 &= 5, \\ (a + b + c + d + e)(a^3 + b^3 + c^3 + d^3 + e^3) &= 25. \end{align*}
31
0
27,938
Find the largest integer $n$ for which $2^n$ divides \[ \binom 21 \binom 42 \binom 63 \dots \binom {128}{64}. \]*Proposed by Evan Chen*
193
82.03125
27,939
In rectangle \(ABCD\), \(\overline{AB}=30\) and \(\overline{BC}=15\). Let \(E\) be a point on \(\overline{CD}\) such that \(\angle CBE=45^\circ\) and \(\triangle ABE\) is isosceles. Find \(\overline{AE}.\)
15
12.5
27,940
What is the total number of digits used when the first 2500 positive even integers are written?
9449
4.6875
27,941
Given an ellipse $C$: $\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 (a > b > 0)$, where the upper vertex of $C$ is $A$, and the two foci are $F_{1}$ and $F_{2}$, with an eccentricity of $\frac{1}{2}$. A line passing through $F_{1}$ and perpendicular to $AF_{2}$ intersects $C$ at points $D$ and $E$, where $|DE| = 6$. Find the perimeter of $\triangle ADE$.
13
14.84375
27,942
What is the smallest positive integer with exactly 16 positive divisors?
120
90.625
27,943
What is the least positive integer with exactly $12$ positive factors?
72
0
27,944
Students are in classroom with $n$ rows. In each row there are $m$ tables. It's given that $m,n \geq 3$ . At each table there is exactly one student. We call neighbours of the student students sitting one place right, left to him, in front of him and behind him. Each student shook hands with his neighbours. In the end there were $252$ handshakes. How many students were in the classroom?
72
3.125
27,945
In $\triangle ABC$, $\angle A = 60^{\circ}$ and $AB > AC$. Point $O$ is the circumcenter, and the altitudes $BE$ and $CF$ intersect at point $H$. Points $M$ and $N$ lie on segments $BH$ and $HF$, respectively, such that $BM = CN$. Find the value of $\frac{MH + NH}{OH}$.
\sqrt{3}
0.78125
27,946
A circle is inscribed in quadrilateral $EFGH$, tangent to $\overline{EF}$ at $R$ and to $\overline{GH}$ at $S$. Given that $ER=25$, $RF=35$, $GS=40$, and $SH=20$, and that the circle is also tangent to $\overline{EH}$ at $T$ with $ET=45$, find the square of the radius of the circle.
3600
0
27,947
There is a beach soccer tournament with 17 teams, where each team plays against every other team exactly once. A team earns 3 points for a win in regular time, 2 points for a win in extra time, and 1 point for a win in a penalty shootout. The losing team earns no points. What is the maximum number of teams that can each earn exactly 5 points?
11
3.90625
27,948
Given a structure formed by joining eight unit cubes where one cube is at the center, and each face of the central cube is shared with one additional cube, calculate the ratio of the volume to the surface area in cubic units to square units.
\frac{4}{15}
8.59375
27,949
Given a right rectangular prism $B$ with edge lengths $1,$ $3,$ and $4$, and the set $S(r)$ of points within a distance $r$ of some point in $B$, express the volume of $S(r)$ as $ar^{3} + br^{2} + cr + d$ and determine the ratio $\frac{bc}{ad}$.
19
8.59375
27,950
Each row of a $24 \times 8$ table contains some permutation of the numbers $1, 2, \cdots , 8.$ In each column the numbers are multiplied. What is the minimum possible sum of all the products? *(C. Wu)*
8 * (8!)^3
0
27,951
Santa Claus has 36 identical gifts divided into 8 bags. The number of gifts in each of the 8 bags is at least 1 and all are different. You need to select some of these bags to evenly distribute all their gifts to 8 children, such that all gifts are distributed completely (each child receives at least one gift). How many different selections are there?
31
25
27,952
Five persons wearing badges with numbers $1, 2, 3, 4, 5$ are seated on $5$ chairs around a circular table. In how many ways can they be seated so that no two persons whose badges have consecutive numbers are seated next to each other? (Two arrangements obtained by rotation around the table are considered different)
10
72.65625
27,953
What is the minimum number of shots required in the game "Battleship" on a 7x7 board to definitely hit a four-cell battleship (which consists of four consecutive cells in a single row)?
12
4.6875
27,954
In triangle $XYZ$, $XY = 15$, $XZ = 17$, and $YZ = 24$. The medians $XM$, $YN$, and $ZL$ of triangle $XYZ$ intersect at the centroid $G$. Let $Q$ be the foot of the altitude from $G$ to $YZ$. Find $GQ$.
3.5
0
27,955
Let $\mathcal{T}$ be the set of real numbers that can be represented as repeating decimals of the form $0.\overline{abcd}$ where $a, b, c, d$ are distinct digits. Find the sum of the elements of $\mathcal{T}.$
2520
9.375
27,956
Find the smallest positive integer $k$ such that, for any subset $A$ of $S=\{1,2,\ldots,2012\}$ with $|A|=k$ , there exist three elements $x,y,z$ in $A$ such that $x=a+b$ , $y=b+c$ , $z=c+a$ , where $a,b,c$ are in $S$ and are distinct integers. *Proposed by Huawei Zhu*
1008
8.59375
27,957
Five squares and two right-angled triangles are positioned as shown. The areas of three squares are \(3 \, \mathrm{m}^{2}, 7 \, \mathrm{m}^{2}\), and \(22 \, \mathrm{m}^{2}\). What is the area, in \(\mathrm{m}^{2}\), of the square with the question mark? A) 18 B) 19 C) 20 D) 21 E) 22
18
10.15625
27,958
In the diagram, triangle \(ABC\) is isosceles, with \(AB = AC\). If \(\angle ABC = 50^\circ\) and \(\angle DAC = 60^\circ\), the value of \(x\) is:
70
10.9375
27,959
How many of the smallest 2401 positive integers written in base 7 include the digits 4, 5, or 6?
2146
4.6875
27,960
The 31st World University Summer Games will be held in Chengdu, Sichuan from July 28th to August 8th, 2023. A company decided to evaluate a certain product under its umbrella for bidding for related endorsement activities. The original selling price of the product was $25 per unit, with an annual sales volume of 80,000 units. $(1)$ According to market research, if the price is increased by $1, the sales volume will decrease by 2,000 units. To ensure that the total revenue from sales is not less than the original revenue, what is the maximum price per unit that the product can be priced at? $(2)$ To seize this opportunity, expand the influence of the product, and increase the annual sales volume, the company decided to immediately carry out a comprehensive technological innovation and marketing strategy reform on the product, and increase the price to $x per unit. The company plans to invest $\frac{1}{6}(x^{2}-600)$ million as a technological innovation cost, $50$ million as fixed advertising costs, and $\frac{x}{5}$ million as variable advertising costs. What is the minimum sales volume $a$ that the product should reach after the reform in order to ensure that the sales revenue after the reform is not less than the original revenue plus the total investment? Also, determine the price per unit of the product at this point.
30
6.25
27,961
In tetrahedron \( SABC \), the circumradius of triangles \( \triangle SAB \), \( \triangle SBC \), and \( \triangle SCA \) are all 108. The center of the inscribed sphere is \( I \) and \( SI = 125 \). Let \( R \) be the circumradius of \( \triangle ABC \). If \( R \) can be expressed as \( \sqrt{\frac{m}{n}} \) (where \( m \) and \( n \) are positive integers and \(\gcd(m, n) = 1\)), what is \( m+n \)?
11665
1.5625
27,962
Consider a square pyramid $S-ABCD$ with a height of $h$. The base $ABCD$ is a square with side length 1. Points $S$, $A$, $B$, $C$, and $D$ all lie on the surface of a sphere with radius 1. The task is to find the distance between the center of the base $ABCD$ and the vertex $S$.
\frac{\sqrt{2}}{2}
27.34375
27,963
In the diagram below, $ABCD$ is a trapezoid such that $\overline{AB}\parallel \overline{CD}$ and $\overline{AC}\perp\overline{CD}$. If $CD = 15$, $\tan C = 2$, and $\tan B = \frac{3}{2}$, then what is $BD$?
10\sqrt{13}
10.15625
27,964
Given that the discrete random variable \\(\xi\\) follows a normal distribution \\(N \sim (2,1)\\), and \\(P(\xi < 3) = 0.968\\), then \\(P(1 < \xi < 3) =\\) \_\_\_\_\_\_.
0.936
40.625
27,965
Juan rolls a fair regular decagonal die marked with numbers from 1 to 10. Then Amal rolls a fair eight-sided die marked with numbers from 1 to 8. What is the probability that the product of the two rolls is a multiple of 4?
\frac{19}{40}
8.59375
27,966
What is the number of square units in the area of trapezoid EFGH with vertices E(0,0), F(0,3), G(5,3), and H(3,0)?
7.5
41.40625
27,967
In a tetrahedron \(ABCD\), \(AD = \sqrt{2}\) and all other edge lengths are 1. Find the shortest path distance from the midpoint \(M\) of edge \(AB\) to the midpoint \(N\) of edge \(CD\) along the surface of the tetrahedron.
\frac{\sqrt{3}}{2}
20.3125
27,968
Find the probability \( P(B^c | A^c) \) given the probabilities: \[ P(A \cap B) = 0.72, \quad P(A \cap \bar{B}) = 0.18 \]
0.90
0
27,969
How many of the natural numbers from 1 to 800, inclusive, contain the digit 7 at least once?
152
0
27,970
How many of the 512 smallest positive integers written in base 8 use 5 or 6 (or both) as a digit?
296
0.78125
27,971
A community organization begins with twenty members, among which five are leaders. The leaders are replaced annually. Each remaining member persuades three new members to join the organization every year. Additionally, five new leaders are elected from outside the community each year. Determine the total number of members in the community five years later.
15365
10.15625
27,972
The function $f(x)=1+x- \frac {x^{2}}{2}+ \frac {x^{3}}{3}$, $g(x)=1-x+ \frac {x^{2}}{2}- \frac {x^{3}}{3}$, if the function $F(x)=f(x+3)g(x-4)$, and the zeros of the function $F(x)$ are all within $[a,b]$ $(a < b$, $a$, $b\in\mathbb{Z})$, then the minimum value of $b-a$ is \_\_\_\_\_\_.
10
17.1875
27,973
Let ellipse $C$:$\frac{{x}^{2}}{{a}^{2}}+\frac{{y}^{2}}{{b}^{2}}=1\left(a \gt b \gt 0\right)$ have foci $F_{1}(-c,0)$ and $F_{2}(c,0)$. Point $P$ is the intersection point of $C$ and the circle $x^{2}+y^{2}=c^{2}$. The bisector of $\angle PF_{1}F_{2}$ intersects $PF_{2}$ at $Q$. If $|PQ|=\frac{1}{2}|QF_{2}|$, then find the eccentricity of ellipse $C$.
\sqrt{3}-1
0
27,974
In $\triangle ABC,$ $AB=20$, $AC=24$, and $BC=18$. Points $D,E,$ and $F$ are on sides $\overline{AB},$ $\overline{BC},$ and $\overline{AC},$ respectively. Angle $\angle BAC = 60^\circ$ and $\overline{DE}$ and $\overline{EF}$ are parallel to $\overline{AC}$ and $\overline{AB},$ respectively. What is the perimeter of parallelogram $ADEF$?
44
18.75
27,975
What is the largest four-digit negative integer congruent to $2 \pmod{25}$?
-1023
20.3125
27,976
The least common multiple of $a$ and $b$ is $18$, and the least common multiple of $b$ and $c$ is $20$. Find the least possible value of the least common multiple of $a$ and $c$.
90
27.34375
27,977
Given an ellipse $\dfrac {x^{2}}{a^{2}}+ \dfrac {y^{2}}{b^{2}}=1$ with its left and right foci being $F_{1}$ and $F_{2}$ respectively, a perpendicular line to the x-axis through the left focus $F_{1}(-2,0)$ intersects the ellipse at points $P$ and $Q$. The line $PF_{2}$ intersects the y-axis at $E(0, \dfrac {3}{2})$. $A$ and $B$ are points on the ellipse located on either side of $PQ$. - (I) Find the eccentricity $e$ and the standard equation of the ellipse; - (II) When $\angle APQ=\angle BPQ$, is the slope $K_{AB}$ of line $AB$ a constant value? If so, find this constant value; if not, explain why.
- \dfrac {1}{2}
0
27,978
Bryan has some stamps of 3 cents, 4 cents, and 6 cents. What is the least number of stamps he can combine so the value of the stamps is 50 cents?
10
53.90625
27,979
At 17:00, the speed of a racing car was 30 km/h. Every subsequent 5 minutes, the speed increased by 6 km/h. Determine the distance traveled by the car from 17:00 to 20:00 on the same day.
425.5
0
27,980
Given that the plane vectors $\overrightarrow{a}$, $\overrightarrow{b}$, $\overrightarrow{c}$ satisfy $|\overrightarrow{a}|=1$, $|\overrightarrow{b}|=2$, and for all $t\in \mathbb{R}$, $|\overrightarrow{b}+t\overrightarrow{a}| \geq |\overrightarrow{b}-\overrightarrow{a}|$ always holds, determine the angle between $2\overrightarrow{a}-\overrightarrow{b}$ and $\overrightarrow{b}$.
\frac{2\pi}{3}
89.0625
27,981
Given vectors $\overrightarrow{a}=(1,3)$ and $\overrightarrow{b}=(-2,4)$, calculate the projection of $\overrightarrow{a}$ in the direction of $\overrightarrow{b}$.
\sqrt{5}
0
27,982
For a nonnegative integer $n$, let $r_7(n)$ represent the remainder when $n$ is divided by $7$. Determine the $15^{\text{th}}$ entry in an ordered list of all nonnegative integers $n$ that satisfy $$r_7(3n)\le 3.$$
22
21.875
27,983
Use the Horner's method to compute the value of the polynomial $f(x)=0.5x^{5}+4x^{4}-3x^{2}+x-1$ when $x=3$, and determine the first operation to perform.
5.5
0.78125
27,984
Given two squares $ABCD$ and $DCFE$ with side lengths of $1$, where the planes they reside in are perpendicular to each other. Points $P$ and $Q$ are moving points on line segments $BC$ and $DE$ (including endpoints), with $PQ = \sqrt{2}$. Let the trajectory of the midpoint of line segment $PQ$ be curve $\mathcal{A}$. Determine the length of $\mathcal{A}$.
\frac{\pi}{4}
4.6875
27,985
Let \( f : \mathbb{C} \to \mathbb{C} \) be defined by \( f(z) = z^2 - 2iz + 2 \). Determine how many complex numbers \( z \) exist such that \( \text{Im}(z) > 0 \) and both the real and the imaginary parts of \( f(z) \) are integers within \( |a|, |b| \leq 5 \).
110
0
27,986
What is the sum of the squares of the lengths of the medians of a triangle whose side lengths are $13, 13,$ and $10$?
432
1.5625
27,987
Anya, Vanya, Danya, and Tanya collected apples. Each of them collected a whole number percentage from the total number of apples, and all these numbers are distinct and more than zero. Then Tanya, who collected the most apples, ate her apples. After that, each of the remaining kids still had a whole percentage of the remaining apples. What is the minimum number of apples that could have been collected?
20
0
27,988
A triangle has vertices \( P=(-7,4) \), \( Q=(-14,-20) \), and \( R=(2,-8) \). The equation of the bisector of \( \angle P \) can be written in the form \( ax+2y+c=0 \). Find \( a+c \).
40
0
27,989
The increasing sequence consists of all those positive integers which are either powers of 2, powers of 3, or sums of distinct powers of 2 and 3. Find the $50^{\rm th}$ term of this sequence.
57
7.8125
27,990
Find the number of six-digit palindromes.
900
91.40625
27,991
\(ABCD\) is a square with sides \(8 \, \text{cm}\). \(M\) is a point on \(CB\) such that \(CM = 2 \, \text{cm}\). If \(N\) is a variable point on the diagonal \(DB\), find the least value of \(CN + MN\).
10
17.1875
27,992
There is a positive integer s such that there are s solutions to the equation $64sin^2(2x)+tan^2(x)+cot^2(x)=46$ in the interval $(0,\frac{\pi}{2})$ all of the form $\frac{m_k}{n_k}\pi$ where $m_k$ and $n_k$ are relatively prime positive integers, for $k = 1, 2, 3, . . . , s$ . Find $(m_1 + n_1) + (m_2 + n_2) + (m_3 + n_3) + · · · + (m_s + n_s)$ .
100
0
27,993
The first number in the following sequence is $1$ . It is followed by two $1$ 's and two $2$ 's. This is followed by three $1$ 's, three $2$ 's, and three $3$ 's. The sequence continues in this fashion. \[1,1,1,2,2,1,1,1,2,2,2,3,3,3,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,\dots.\] Find the $2014$ th number in this sequence.
13
0.78125
27,994
In triangle $ABC$, the altitude and the median from vertex $C$ each divide the angle $ACB$ into three equal parts. Determine the ratio of the sides of the triangle.
2 : \sqrt{3} : 1
1.5625
27,995
Given that vectors $\overrightarrow{OA}$ and $\overrightarrow{OB}$ are perpendicular and $|\overrightarrow{OA}| = |\overrightarrow{OB}| = 24$. If $t \in [0,1]$, the minimum value of $|t \overrightarrow{AB} - \overrightarrow{AO}| + \left|\frac{5}{12} \overrightarrow{BO} - (1-t) \overrightarrow{BA}\right|$ is:
26
12.5
27,996
From a \(6 \times 6\) square grid, gray triangles were cut out. What is the area of the remaining shape? The length of each side of the cells is 1 cm. Provide your answer in square centimeters.
27
46.875
27,997
Given a cube, calculate the total number of pairs of diagonals on its six faces, where the angle formed by each pair is $60^{\circ}$.
48
5.46875
27,998
In $\triangle ABC$, the sides opposite to angles $A$, $B$, $C$ are $a$, $b$, $c$ respectively. The vectors $m=(\cos (A-B),\sin (A-B))$, $n=(\cos B,-\sin B)$, and $m\cdot n=-\frac{3}{5}$. (1) Find the value of $\sin A$. (2) If $a=4\sqrt{2}$, $b=5$, find the measure of angle $B$ and the projection of vector $\overrightarrow{BA}$ onto the direction of $\overrightarrow{BC}$.
\frac{\sqrt{2}}{2}
3.125
27,999
An ellipse $\frac {x^{2}}{a^{2}}+ \frac {y^{2}}{b^{2}}=1 (a>b>0)$ has its two foci and the endpoints of its minor axis all lying on the circle $x^{2}+y^{2}=1$. A line $l$ (not perpendicular to the x-axis) passing through the right focus intersects the ellipse at points A and B. The perpendicular bisector of segment AB intersects the x-axis at point P. (1) Find the equation of the ellipse; (2) Investigate whether the ratio $\frac {|AB|}{|PF|}$ is a constant value. If it is, find this constant value. If not, explain why.
2 \sqrt {2}
0