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math
In the regular pyramid $S$-$ABCD$, $O$ is the projection of the apex on the base, $P$ is the midpoint of the lateral edge $SD$, and $SO = OD$. The angle formed by line $BC$ and plane $PAC$ is ______.
30^\circ
60
4
math
Given triangle $ABC$, if $\sin A + 2\sin B\cos C = 0$, find the maximum value of $\tan A$.
\frac{1}{\sqrt{3}}
31
10
math
Given that in $\triangle ABC$, $C = 2A$, $\cos A = \frac{3}{4}$, and $2 \overrightarrow{BA} \cdot \overrightarrow{CB} = -27$. (I) Find the value of $\cos B$; (II) Find the perimeter of $\triangle ABC$.
15
71
2
math
The function \(f(x) = 5x^2 - 15x - 2\) has a minimum value when x is negative.
-13.25
30
6
math
If $a^{m}=2$ and $a^{n}=3$, then $a^{m+n}=$______, $a^{m-2n}=$______.
\frac{2}{9}
37
7
math
Let $s$ be the result of tripling both the base and exponent of $c^d$, where $d$ is a non-zero integer. If $s$ equals the product of $c^d$ by $y^d$, determine the value of $y$.
27c^2
57
5
math
In how many distinct ways can I arrange my six keys on a keychain, if I want to put my house key next to my car key and my mailbox key next to my bike key? Two arrangements are not considered different if the keys are in the same order (or can be made to be in the same order without taking the keys off the chain--that ...
3
80
1
math
For constants $a$ and $b$, let \[f(x) = \left\{ \begin{array}{cl} ax + b & \text{if } x < 1, \\ 7 - 2x & \text{if } x \ge 1. \end{array} \right.\] The function $f$ has the property that $f(f(x)) = x$ for all $x$. What is the value of $a + b$?
3
101
1
math
John is deciding whether to go hiking tomorrow. If it rains, there is a 10% chance he will go hiking, but if it is sunny, there is a 90% chance he will go. The weather forecast predicts a 30% chance of rain. What is the probability that John will go hiking? Express your answer as a percent.
66\%
74
4
math
The interval that contains the root of the function $f(x) = x^5 + x - 3$ is to be found.
[1,2]
28
5
math
Given a 3 cm by 3 cm by 3 cm cube, a 1 cm by 1 cm by 1 cm cube is cut from one corner and a 2 cm by 2 cm by 2 cm cube is cut from the opposite corner, calculate the surface area of the resulting solid.
54
63
2
math
Given that $\frac{n}{p\_1+p\_2+...+p\_n}$ is the "harmonic mean" of $n$ positive numbers $p\_1$, $p\_2$, ..., $p\_n$, and the harmonic mean of the first $n$ terms of the sequence $\{a\_n\}$ is $\frac{1}{n}$, determine the value of $\frac{1}{a\_1a\_2} + \frac{1}{a\_2a\_3} + ... + \frac{1}{a\_10a\_11}$.
\frac{10}{21}
125
9
math
Given the sets $A=\{x\mid ax-2=0\}$ and $B=\{x\mid x^2-3x+2=0\}$, and $A \subseteq B$, then the set $C$ consisting of the values of the real number $a$ is
\{1, 2\}
63
8
math
Fifty slips are placed into a hat, each bearing a number from 1 to 10, with each number entered on five slips. Five slips are drawn from the hat at random and without replacement. Let $p$ be the probability that all five slips bear the same number. Let $q$ be the probability that two of the slips bear a number $a$ and ...
450
99
3
math
At the World Meteorological Conference, each participant took turns announcing the average monthly temperature in their home city. Meanwhile, all others recorded the product of the temperature in their city and the temperature being announced. In total, 62 positive numbers and 48 negative numbers were recorded. What is...
3
72
1
math
What is the largest 4-digit integer congruent to $7 \pmod{19}$?
9982
21
4
math
Derive the formula \( I_{2}^{*}=\frac{1}{n} \sum_{i=1}^{n} \frac{\varphi\left(x_{i}\right)}{f\left(x_{i}\right)} \) for estimating the definite integral \( I=\int_{a}^{b} \varphi(x) \, \mathrm{d} x \), where \( f(x) \) is the density of an auxiliary random variable \( X \) in the integration interval \( (a, b) \); \( x...
I_{2}^{*} = \frac{1}{n} \sum_{i=1}^{n} \frac{\varphi(x_i)}{f(x_i)}
153
38
math
In $\triangle ABC$, the sides opposite to angles A, B, and C are $a$, $b$, and $c$, respectively. If $$\frac{a^2}{bc} - \frac{c}{b} - \frac{b}{c} = \sqrt{3}$$, and the radius of the circumcircle of $\triangle ABC$ is 3, find $a$.
a = 3
84
4
math
Given that Alice and Bob shared a large pizza cut into 12 equally-sized slices, the cost of the plain pizza was $12, and there was an additional cost of $4 to add olives to three slices, find the difference in the amount Bob paid and the amount Alice paid, after Bob ate all the olive-topped slices and 3 slices of the p...
0
87
1
math
Two lines passing through point \( M \), which lies outside the circle with center \( O \), touch the circle at points \( A \) and \( B \). Segment \( OM \) is divided in half by the circle. In what ratio is segment \( OM \) divided by line \( AB \)?
1:3
63
3
math
For every $m$ and $k$ integers with $k$ odd and a divisor of 150, denote by $\left[\frac{m}{k}\right]$ the integer closest to $\frac{m}{k}$. For every odd integer $k$ that divides 150, let $P(k)$ be the probability that \[\left[\frac{n}{k}\right] + \left[\frac{150 - n}{k}\right] = \left[\frac{150}{k}\right]\] for an in...
\frac{1}{5}
237
7
math
Vanya came up with a three-digit prime number in which all digits are different. What digit can it end with if its last digit is equal to the sum of the first two digits?
7
38
1
math
Given the function $f(x)=2\sin (2x+ \frac {\pi}{6})-1$ $(x\in\mathbb{R})$, find the maximum and minimum values of $f(x)$ in the interval $\left[0, \frac {\pi}{2}\right]$.
-2
64
2
math
Sequence $(a_n)$ is defined as $a_{n+1}-2a_n+a_{n-1}=7$ for every $n\geq 2$ , where $a_1 = 1, a_2=5$ . What is $a_{17}$ ?
905
69
3
math
A circle of radius $15$ inches has its center at the vertex $C$ of an equilateral triangle $ABC$ and passes through the other two vertices. The side $BC$ extended through $C$ intersects the circle at point $E$. Find the number of degrees in angle $AEC$.
90
63
2
math
Given a number $n\in\mathbb{Z}^+$ and let $S$ denotes the set $\{0,1,2,...,2n+1\}$ . Consider the function $f:\mathbb{Z}\times S\to [0,1]$ satisfying two following conditions simultaneously: i) $f(x,0)=f(x,2n+1)=0\forall x\in\mathbb{Z}$ ; ii) $f(x-1,y)+f(x+1,y)+f(x,y-1)+f(x,y+1)=1$ for all $x\in\mathbb{Z}$ ...
2n + 1
273
5
math
In the exam, there were 25 problems of three types: easy ones worth 2 points each, medium ones worth 3 points each, and hard ones worth 5 points each. Correctly solved problems were rewarded with the specified points based on difficulty; otherwise, they received 0 points. The best possible total score on the exam was 8...
40
107
2
math
Let $n$ be a positive integer such that the decimal representation of $n!$ ends in $k$ zeros and the decimal representation of $(3n)!$ ends in $4k$ zeros. Let $t$ denote the sum of the four smallest possible values of $n$. Find the sum of the digits of $t$.
7
69
1
math
Given $x∈({0,\frac{π}{2}})$, and $ax \lt \sin x \lt bx$ always holds, find the minimum value of $b-a$.
1-\frac{2}{π}
39
8
math
Given that the function $f(x) = -x^3 + ax^2 - 4$ attains an extremum at $x = 2$, and if $m, n \in [-1,1]$, then the minimum value of $f(m) + f'(n)$ is ______.
-4 + (-9) = -13
64
10
math
\(\left(\frac{3}{5}\right)^{2 \log _{9}(x+1)} \cdot\left(\frac{125}{27}\right)^{\log _{v 27}(x-1)}=\frac{\log _{5} 27}{\log _{5} 243}\).
x = 2
77
4
math
Michael picks a random subset of the complex numbers \(\left\{1, \omega, \omega^{2}, \ldots, \omega^{2017}\right\}\) where \(\omega\) is a primitive \(2018^{\text {th }}\) root of unity and all subsets are equally likely to be chosen. If the sum of the elements in his subset is \(S\), what is the expected value of \(|S...
\frac{1009}{2}
115
10
math
Find the remainder when the polynomial $x^{1002}$ is divided by the polynomial $(x^2 - 1)(x + 1).$
1
33
1
math
How many two digit numbers have exactly $4$ positive factors? $($ Here $1$ and the number $n$ are also considered as factors of $n. )$
31
45
2
math
Given the function $g(x)=x^{2}-2 (x \in \mathbb{R})$ and $f(x) = \begin{cases} g(x)+x+4, & x < g(x) \\ g(x)-x, & x \geq g(x) \end{cases}$, determine the range of $f(x)$.
[-2.25, 0] \cup (2, +\infty)
76
19
math
Given the ellipse \(\frac{x^{2}}{5^{2}}+\frac{y^{2}}{4^{2}}=1\), a line passes through its left focus \(F_{1}\) and intersects the ellipse at points \(A\) and \(B\). Point \(D(a, \theta)\) is located to the right of \(F_{1}\). The lines \(AD\) and \(BD\) intersect the left directrix of the ellipse at points \(M\) and \...
a = 5
135
4
math
My friend thought of an integer between 10 and 19. To guess the number he thought of, I can ask him questions that he will answer with "yes" or "no": What is the minimum number of questions, and which questions should I ask to determine the number he thought of?
3
62
1
math
In an isosceles right triangle \( \triangle ABC \), \( \angle A = 90^\circ \), \( AB = 1 \). \( D \) is the midpoint of \( BC \), \( E \) and \( F \) are two other points on \( BC \). \( M \) is the other intersection point of the circumcircles of \( \triangle ADE \) and \( \triangle ABF \); \( N \) is the other inters...
\sqrt{2}
154
5
math
Find the sum of the thousands digit and the units digit of the product of the two 101-digit numbers 404040404...040404 and 707070707...070707.
10
59
2
math
Observe the following equations: $$1^{2}=1$$ $$1^{2}-2^{2}=-3$$ $$1^{2}-2^{2}+3^{2}=6$$ $$1^{2}-2^{2}+3^{2}-4^{2}=-10$$ $$\ldots$$ According to this pattern, the $n^{th}$ equation can be written as \_\_\_\_\_\_.
1^{2}-2^{2}+3^{2}-\ldots+(-1)^{n-1}n^{2}=\frac{(-1)^{n+1}}{2}n(n+1)
96
48
math
Let \( b = 1^{2} - 2^{2} + 3^{2} - 4^{2} + 5^{2} - \ldots - 2012^{2} + 2013^{2} \). Determine the remainder of \( b \) divided by 2015.
1
73
1
math
Given a complex number $Z$ that satisfies the equation $Z(i-1)=2i$ (where $i$ is the imaginary unit), determine $\overset{.}{Z}$.
1+i
40
2
math
Let the function $f(x)=x^{3}+x$, where $x\in\mathbb{R}$. If for $0 < \theta < \frac{\pi}{2}$, the inequality $f(m\sin \theta)+f(1-m) > 0$ always holds, determine the range of the real number $m$.
(-\infty, 1]
74
8
math
How many integers between $200$ and $250$ have three different digits in decreasing order?
1
23
1
math
In a rectangle of size $3 \times 4$, 4 points are chosen. Find the smallest number $C$ such that the distance between some two of these points does not exceed $C$.
2.5
41
3
math
\[\left\{\begin{array}{l} 3(2-\sqrt{x-y})^{-1}+10(2+\sqrt{x+y})^{-1}=5, \\ 4(2-\sqrt{x-y})^{-1}-5(2+\sqrt{x+y})^{-1}=3. \end{array}\right.\] \[\left\{\begin{array}{l} \sqrt[3]{x}+\sqrt[3]{y}=4, \\ x+y=28. \end{array}\right.\]
(1, 27), (27, 1)
112
14
math
Each corner cube is removed from this $3\text{ cm}\times 3\text{ cm}\times 3\text{ cm}$ cube. The surface area of the remaining figure is [asy] draw((2.7,3.99)--(0,3)--(0,0)); draw((3.7,3.99)--(1,3)--(1,0)); draw((4.7,3.99)--(2,3)--(2,0)); draw((5.7,3.99)--(3,3)--(3,0)); draw((0,0)--(3,0)--(5.7,0.99)); draw((0,1)--(3,1...
54
324
2
math
The monotonic decreasing interval of the function $f\left(x\right)={\left( \frac{1}{3}\right)}^{-{x}^{2}-4x+3}$ is \_\_\_\_\_\_.
(-\infty, -2]
49
8
math
Find the values of $x$ and $y$ such that $\sqrt{4 - 5x + y} = 9$.
y = 77 + 5x
28
9
math
Let the function $f(x)$ be defined on $\mathbb{R}$ and satisfy $f(2-x) = f(2+x)$ and $f(7-x) = f(7+x)$. Also, in the closed interval $[0, 7]$, only $f(1) = f(3) = 0$. Determine the number of roots of the equation $f(x) = 0$ in the closed interval $[-2005, 2005]$.
802
107
3
math
Given $\triangle BAD$ is right-angled at $B$, on $AD$ there is a point $C$ for which $AC=CD$ and $AB=BC$. Determine the magnitude of $\angle DAB$.
60^\circ
46
4
math
A train departs from point $A$ and travels towards point $B$ at a uniform speed. 11 minutes later, another train departs from point $B$ traveling towards point $A$ at a constant speed on the same route. After their meeting point, it takes the trains 20 minutes and 45 minutes to reach $B$ and $A$, respectively. In what ...
9/5
97
3
math
Let $x$ and $y$ be positive real numbers. Find the minimum value of \[ \frac{\sqrt{(x^2 + y^2)(4x^2 + 2y^2)}}{xy}. \]
2 + \sqrt{2}
50
7
math
A positive integer will be called "sparkly" if its smallest positive divisor, other than 1, equals the total number of divisors (including 1). How many of the numbers \(2, 3, \ldots, 2003\) are sparkly?
3
58
1
math
Given a quadratic equation in terms of $x$: $mx^{2}-4x+1=0$. $(1)$ If $1$ is one of the roots of this equation, find the value of $m$; $(2)$ If the quadratic equation $mx^{2}-4x+1=0$ has real roots, find the range of values for $m$.
m \leq 4 \text{ and } m \neq 0
80
17
math
Ann wants to build a $6$-step staircase using toothpicks. She already made a $4$-step staircase using $28$ toothpicks. The number of toothpicks added for each additional step increases by $3$ more than the previous step's increase. Calculate the total number of additional toothpicks Ann needs to complete the $6$-step s...
33
80
2
math
Given that $\frac{a}{30-a}+\frac{b}{70-b}+\frac{c}{75-c}=9$, evaluate $\frac{6}{30-a}+\frac{14}{70-b}+\frac{15}{75-c}$.
35
62
2
math
Given the variable $a$ and $θ∈R$, find the minimum value of $(a-2\cos θ)^{2}+(a-5 \sqrt {2}-2\sin θ)^{2}$.
9
48
1
math
A rug is made with three different colors as shown. The areas of the three differently colored regions form an arithmetic progression. The inner rectangle is two feet wide, and each of the two shaded regions is $2$ feet wide on all four sides. Find the length in feet of the inner rectangle.
4
60
1
math
If \(x\), \(y\), and \(z\) are positive real numbers with \(xy = 30\), \(xz = 60\), and \(yz = 90\), what is the value of \(x+y+z\)?
11\sqrt{5}
54
7
math
Let \( m = 2^{40}5^{24} \). How many positive integer divisors of \( m^2 \) are less than \( m \) but do not divide \( m \)?
959
45
3
math
Given the set \( S = \{1, 2, \cdots, 2005\} \), and a subset \( A \subseteq S \) such that the sum of any two numbers in \( A \) is not divisible by 117, determine the maximum value of \( |A| \).
1003
69
4
math
The value of 1 + 3^2 is
10
11
2
math
When I saw Eleonora, I found her very pretty. After a brief trivial conversation, I told her my age and asked how old she was. She answered: - When you were as old as I am now, you were three times older than me. And when I will be three times older than I am now, together our ages will sum up to exactly a century. ...
15
87
2
math
A regular octagon and a rectangle share a common side \( \overline{AD} \). Determine the degree measure of the exterior angle \( BAC \) formed at vertex \( A \) where \( \angle BAD \) is an angle of the octagon and \( \angle CAD \) is an angle of the rectangle.
135^\circ
68
5
math
Find the standard equations for the following curves: (1) A parabola whose focus is the left vertex of the ellipse $\frac{x^2}{9} + \frac{y^2}{16} = 1$; (2) A hyperbola that shares asymptotes with the hyperbola $\frac{y^2}{5} - \frac{x^2}{5} = 1$ and passes through the point $(1, \sqrt{3})$.
\frac{y^2}{2} - \frac{x^2}{2} = 1
101
21
math
In the plane rectangular coordinate system $xOy$, the parameter equation of the line $l$ is $\left\{{\begin{array}{l}{x=3-\frac{{\sqrt{3}}}{2}t,}\\{y=\sqrt{3}-\frac{1}{2}t}\end{array}}\right.$ (where $t$ is the parameter). Establish a polar coordinate system with the origin $O$ as the pole and the positive half-axis of...
\frac{\sqrt{3}}{2}
243
10
math
Provide the proof process for the following inequalities: \\(①\\) If \\(a\\), \\(b∈R\\), then \\(\dfrac{b}{a}+\dfrac{a}{b}\geqslant 2\sqrt{\dfrac{b}{a}\cdot \dfrac{a}{b}}=2\\); \\(②\\) If \\(x > 0\\), then \\(\cos x+\dfrac{1}{\cos x}\geqslant 2\sqrt{\cos x\cdot \dfrac{1}{\cos x}}=2\\); \\(③\\) If \\(x < 0\\), then \...
①②③
304
6
math
Among the following statements, the correct ones are \_\_\_\_\_\_. ① The set of angles whose terminal sides fall on the y-axis is $$\{α|α= \frac {kπ}{2}, k∈Z\}$$; ② A center of symmetry for the graph of the function $$y=2\cos(x- \frac {π}{4})$$ is $$( \frac {3π}{4}, 0)$$; ③ The function y=tanx is increasing in the ...
②④
173
4
math
The wristwatch is 5 minutes slow per hour; 5.5 hours ago, it was set to the correct time. It is currently 1 PM on a clock that shows the correct time. How many minutes will it take for the wristwatch to show 1 PM?
30
57
2
math
Let $a, b, c, d$ be real numbers, none of which are equal to $-1,$ and let $\omega$ be a complex number such that $\omega^4 = 1$ and $\omega \neq 1.$ If \[ \frac{1}{a + \omega} + \frac{1}{b + \omega} + \frac{1}{c + \omega} + \frac{1}{d + \omega} = \frac{4}{1 + \omega}, \] then find \[ \frac{1}{a + 1} + \frac{1}{b + 1} ...
2
162
1
math
Three friends, Rowan, Sara, and Tim, are playing a monetary game. Each starts with $3. A bell rings every 20 seconds, and with each ring, any player with money chooses one of the other two players independently at random and gives them $1. The game continues for 2020 rounds. What is the probability that at the end of t...
\frac{1}{4}
125
7
math
Given triangle $ABC$ with opposite sides $a$, $b$, and $c$ to angles $A$, $B$, and $C$ respectively, and given that $\sin C= \frac {56}{65}$, $\sin B= \frac {12}{13}$, and $b=3$, find the value of $c$.
\frac {14}{5}
76
8
math
For each integer $1\le j\le 2017$ , let $S_j$ denote the set of integers $0\le i\le 2^{2017} - 1$ such that $\left\lfloor \frac{i}{2^{j-1}} \right\rfloor$ is an odd integer. Let $P$ be a polynomial such that \[P\left(x_0, x_1, \ldots, x_{2^{2017} - 1}\right) = \prod_{1\le j\le 2017} \left(1 - \prod_{i\in S_j} ...
2
257
1
math
**Background:** Define a new operation "$*$": the result of the operation takes the positive sign if the signs are the same, and negative if the signs are different. The value is the sum of their absolute values. When $0$ is operated with any number using "$*$", the result is the absolute value of that number. For exam...
2a + 3
218
5
math
Rectangle $ABCD$ contains a point $Q$ such that the distances from $Q$ to the vertices $A$, $B$, $C$, and $D$ are $5$, $x$, $13$, and $12$ inches respectively. Determine the value of $x$. **A)** $5$ **B)** $7$ **C)** $5\sqrt{2}$ **D)** $13$
5\sqrt{2}
94
6
math
There exists a unique strictly increasing sequence of nonnegative integers $b_1 < b_2 < … < b_m$ such that $\frac{2^{225}+1}{2^{15}+1} = 2^{b_1} + 2^{b_2} + … + 2^{b_m}$, determine the value of $m$.
8
80
1
math
Let $\{a_n\}$ be a decreasing geometric sequence, where $a_1+a_2=11$, $a_1⋅a_2=10$, and $\log{a_1}+\log{a_2}+\log{a_3}+...+\log{a_{10}}=$
-35
70
3
math
In the geometric sequence {a_n}, it is known that $a_1 + a_2 + a_3 = 1$, and $a_4 + a_5 + a_6 = -2$. Find the sum of the first 15 terms of the sequence, $S_{15}$.
S_{15} = 11
66
9
math
A regular dodecahedron is projected orthogonally onto a plane, and its image is an $n$-sided polygon. What is the smallest possible value of $n$ ?
6
41
1
math
Solve the systems of equations: a) $\left\{\begin{array}{l}x^{2}-3 x y-4 y^{2}=0, \\ x^{3}+y^{3}=65 ;\end{array}\right.$ b) $\left\{\begin{array}{l}x^{2}+2 y^{2}=17, \\ 2 x y-x^{2}=3\end{array}\right.$
(3, 2), (-3, -2), \left(\frac{\sqrt{3}}{3}, \frac{5\sqrt{3}}{3}\right), \left(-\frac{\sqrt{3}}{3}, -\frac{5\sqrt{3}}{3}\right)
97
66
math
Given two lines $l_1: (k-3)x + (5-k)y + 1 = 0$ and $l_2: 2(k-3)x - 2y + 3 = 0$ are perpendicular, determine the value(s) of $k$.
1 \text{ or } 4
60
8
math
Express 1.36 billion in scientific notation.
1.36\times 10^{9}
11
12
math
For real numbers \( x \) and \( y \) within the interval \([0, 12]\): $$ xy = (12 - x)^2 (12 - y)^2 $$ What is the maximum value of the product \( xy \)?
81
57
2
math
Given the function $f(x) = \sin\left(\frac{\pi}{6}x\right)\cos\left(\frac{\pi}{6}x\right)$, find the value of $f(1) + f(2) + \ldots + f(2018)$.
0
65
1
math
Find the equation of the line that passes through the intersection point of the lines $x+y-3=0$ and $2x-y=0$, and is perpendicular to the line $2x+y-5=0$.
x - 2y + 3 = 0
46
11
math
Given $a\in R$, the functions are defined as follows: $f(x)=\frac{1}{3}{x^3}-\frac{1}{2}(a-1)x^{2}-ax-3$ and $g\left(x\right)=x-2\ln x$. Find: 1. When $a=1$, find the equation of the tangent line to the function $y=f\left(x\right)$ at the point $\left(3,f\left(3\right)\)$. 2. If the decreasing interval of the function...
(2-2\ln 2, 3-2\ln 3]
189
18
math
Team A and Team B are competing in a table tennis match, with each team having three players. The players for Team A are \( A_1, A_2, A_3 \), and the players for Team B are \( B_1, B_2, B_3 \). According to past competition statistics, the win probabilities between players are as follows: \[ \begin{array}{|c|c|c|} \hl...
E(\xi) = \frac{22}{15}, \quad E(\eta) = \frac{23}{15}
303
30
math
How many even numbers between $1000$ and $9999$ have all distinct digits?
2296
23
4
math
Ben rolls 6 fair 12-sided dice, with each die numbered from 1 to 12. What is the probability that exactly three of the dice show a prime number?
\frac{857500}{2985984}
38
18
math
Let the solution set of the inequality $x(x-a-1)<0$ (where $a \in \mathbb{R}$) be $M$, and the solution set of the inequality $x^2-2x-3\leq0$ be $N$. (Ⅰ) When $a=1$, find the set $M$; (Ⅱ) If $M \subseteq N$, find the range of the real number $a$.
[-2, 2]
98
6
math
Shown below are rows 1, 2, and 3 of Pascal's triangle. \[ \begin{array}{ccccccc} & & 1 & & 1 & & \\ & 1 & & 2 & & 1 & \\ 1 & & 3 & & 3 & & 1 \end{array} \] Let \((d_i), (e_i), (f_i)\) be the sequence, from left to right, of elements in the 2010th, 2011th, and 2012th rows, respectively, with the leftmost element occurr...
\frac{1}{2}
193
7
math
For a positive integer \( n \), let \( x_n \) be the real root of the equation \( n x^{3} + 2 x - n = 0 \). Define \( a_n = \left[ (n+1) x_n \right] \) (where \( [x] \) denotes the greatest integer less than or equal to \( x \)) for \( n = 2, 3, \ldots \). Then find \( \frac{1}{1005} \left( a_2 + a_3 + a_4 + \cdots + a...
2013
138
4
math
Given the function f(x) = e^x(-x + lnx + a), where e is the base of the natural logarithm, a is a constant, and a ≤ 1. (I) Determine whether the function f(x) has an extreme value point in the interval (1, e), and explain the reason. (II) If a = ln2, find the minimum integer value of k such that f(x) < k is always true...
0
94
1
math
Given $\alpha \in (0, \pi)$, if $\sin \alpha + \cos \alpha = \frac{\sqrt{3}}{3}$, calculate the value of $\cos^2 \alpha - \sin^2 \alpha$.
-\frac{\sqrt{5}}{3}
52
10
math
Given $f\left(x\right)=\frac{\sqrt{{x}^{2}+1}+x-1}{\sqrt{{x}^{2}+1}+x+1}+ax^{3}+bx-8$ and $f\left(-2\right)=10$, find $f\left(2\right)=\_\_\_\_\_\_$.
-26
84
3
math
A rectangular container measuring $8\, \text{cm}$ by $4\, \text{cm}$ by $10\, \text{cm}$ is filled with a liquid $Y$ that does not mix with water. When poured into a large body of water, it forms a circular film of thickness $0.05$ cm on the surface. Find the radius, in centimeters, of the resulting circular film.
\sqrt{\frac{6400}{\pi}}
90
13
math
Given the set $A=\{x|x^2-3x+2\leq0\}$, the set $B=\{y|y=x^2-4x+a\}$, and the set $C=\{x|x^2-ax-4\leq0\}$. Proposition $p$: $A\cap B\neq\emptyset$; Proposition $q$: $A\cap C=A$. (1) If proposition $p$ is false, find the range of the real number $a$; (2) If both propositions $p$ and $q$ are true, find the range of th...
[0,6]
142
5
math
Both $a$ and $b$ are positive integers, and $b > 1$. When $a^b$ is the greatest possible value less than 500, and additionally, $a + b$ is even, what is the sum of $a$ and $b$?
24
61
2
math
Given $p$ is an odd prime and $a$ is an integer, find $$ \mid\left\{(x, y) \mid x^2 + y^2 \equiv a \pmod{p}, x, y \in \{0, 1, \ldots, p-1\} \right\}\mid $$
p+1
76
3