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math
Given the function $f(x)=\left| x+\frac{1}{2} \right|+\left| x-\frac{3}{2} \right|$. (Ⅰ) Solve the inequality $f(x)\leqslant 3$; (2) If the solution set of the inequality $f(x) < \frac{1}{2}\left| 1-a \right|$ about $x$ is empty, find the range of the real number $a$.
[-3,5]
102
5
math
Given that θ is in the interval (0, π) and sin2θ = 2 - 2cos2θ, find the value of tanθ.
1
34
1
math
What is the probability that a randomly chosen positive integer is relatively prime to 6? What is the probability that at least one of two randomly chosen integers is relatively prime to 6?
\frac{5}{9}
37
7
math
Given that the vertices of $\triangle ABC$ correspond to the complex numbers $z_1, z_2, z_3$, and satisfy $\left|z_1\right| = \left|z_2\right| = \left|z_3\right| = 1$, express the orthocenter and the center of the nine-point circle of $\triangle ABC$ in terms of $z_1, z_2, z_3$.
\frac{1}{2}(z_1 + z_2 + z_3)
96
19
math
In a math test, $15\%$ of the students scored $65$ points, $25\%$ scored $75$ points, $40\%$ scored $85$ points, and the rest scored $95$ points. Calculate the difference between the mean and median score of this test.
3.5
70
3
math
A merchant buys goods at $25\%$ off the list price. He desires to mark the goods so that he can give a discount of $20\%$ on the marked price and still clear a profit of $25\%$ on the selling price. What percent of the list price must he mark the goods?
125\%
69
5
math
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...
30 \text{ dollars}
301
7
math
Using a steel bar with a total length of 14.8 meters to make the frame of a rectangular container, if one side of the base of the container is 0.5 meters longer than the other side, what height will maximize the volume of the container? Also, find the maximum volume.
1.8
62
3
math
The function $f(x) = x^3 + ax$ ($x \in \mathbb{R}$) has an extremum at $x = l$. Then, the equation of the tangent line to the curve $y = f(x)$ at the origin is ____.
3x + y = 0
57
7
math
A collection of six positive integers has a mean of 5, a unique mode of 4, and a median of 5. If a 9 is added to the collection, what is the new median?
5
43
1
math
The value of the expression \(10 - 10.5 \div [5.2 \times 14.6 - (9.2 \times 5.2 + 5.4 \times 3.7 - 4.6 \times 1.5)]\) is
9.3
63
3
math
Given a linear function $f(x)$ that satisfies $f(f(x))=x+4$. $(1)$ Find the analytical expression of $f(x)$. $(2)$ Let $g(x)=(1-a)x^{2}-x$. If for all $x_{1}\in[\frac{1}{4},4]$, there exists $x_{2}\in[-3,\frac{1}{3}]$ such that $g(x_{1})\geqslant f(x_{2})$, find the range of values for $a$.
(-\infty,\frac{3}{4}]
116
11
math
Determine the domain of the function $$f(x) = \frac{1}{x+9} + \frac{1}{x^2+9} + \frac{1}{x^3+9} + \frac{1}{e^x + 9}.$$
(-\infty, -9) \cup (-9, -\sqrt[3]{9}) \cup (-\sqrt[3]{9}, \infty)
59
35
math
What is the greatest possible common divisor of the numbers \(9m + 7n\) and \(3m + 2n\) if the numbers \(m\) and \(n\) have no common divisors other than one?
3
46
1
math
Given that the total number of passengers is 900, the rental costs of buses A and B are 1600 yuan/bus and 2400 yuan/bus, respectively, and the passenger capacities are 36 people/bus and 60 people/bus, determine the minimum total rental cost.
36800
64
5
math
When point P moves on the circle $x^2-4x+y^2=0$, there exist two fixed points A(1,0) and B(a,0) such that $|PB|=2|PA|$. Find the coordinates of point B.
(-2,0)
55
5
math
Let's define strange numbers in the following way: A single-digit prime number is considered strange. A prime number with at least two digits is considered strange if, by removing either its first or last digit, the resulting number is also a strange number. Determine all the strange numbers.
2, \quad 3, \quad 5, \quad 7, \quad 23, \quad 37, \quad 53, \quad 73, \quad 373
56
47
math
Let the sides opposite to the angles $A$, $B$, $C$ in $\triangle ABC$ be $a$, $b$, $c$, respectively. Let $S$ be the area of $\triangle ABC$, satisfying $S= \frac{ \sqrt{3}}{4}(a^{2}+c^{2}-b^{2})$ (I) Find $B$; (II) If $b=\sqrt{3}$, find the maximum value of $(\sqrt{3}-1)a+2c$.
2 \sqrt {6}
112
6
math
In the Cartesian coordinate plane, the area of the region formed by the points \((x, y)\) that satisfy \( |x| + |y| + |x - 2| \leqslant 4 \) is ______.
12
51
2
math
A point $P$ starts from the origin and moves along the $x$-axis with a velocity $v(t) = 2 - t$ (the positive direction of velocity is consistent with the positive direction of the $x$-axis). Find the distance the point $P$ has moved at $t = 3$.
\frac{5}{2}
68
7
math
Find the sum of all integral values of \( c \) with \( c \leq 30 \) for which the equation \( y = x^2 - 9x - c \) has two rational roots.
-28
46
3
math
In triangle \(PQR,\) \(PQ = 10,\) \(QR = 12,\) \(PR = 14,\) and point \(M\) is the intersection of the medians. Points \(P',\) \(Q',\) and \(R',\) are the images of \(P,\) \(Q,\) and \(R,\) respectively, after a \(180^\circ\) rotation about \(M.\) What is the area of the union of the two regions enclosed by the triangl...
24\sqrt{6}
120
7
math
Two fair dice, each with a different number of faces, are rolled. On each face of each die is printed a distinct integer from 1 to the number of faces on that die, inclusive. The probability of rolling a sum of $8$ is half the probability of rolling a sum of $11$, and the probability of rolling a sum of $15$ is $\frac{...
19
128
2
math
How many positive integers less than 100 that are either prime, or have an even number of positive divisors?
90
25
2
math
In a circle with center $O$, the measure of $\angle RIP$ is $45^\circ$ and $OR=12$ cm. Find the number of centimeters in the length of arc $RP$. Express your answer in terms of $\pi$.
6\pi
54
3
math
Circles $\omega_1$ , $\omega_2$ , and $\omega_3$ are centered at $M$ , $N$ , and $O$ , respectively. The points of tangency between $\omega_2$ and $\omega_3$ , $\omega_3$ and $\omega_1$ , and $\omega_1$ and $\omega_2$ are tangent at $A$ , $B$ , and $C$ , respectively. Line $MO$ intersects $\ome...
\sqrt{3}
210
5
math
Given a regular nonagon \(N\), with \(O\) as the center of its circumcircle, \(PQ\) and \(QR\) as adjacent sides of \(N\). Let \(A\) be the midpoint of \(PQ\), and \(B\) be the midpoint of the radius perpendicular to \(QR\). Find the angle between \(AO\) and \(AB\).
30^{\circ}
78
6
math
A parallelepiped $PQRS TUVW$ is generated by vectors $\overrightarrow{PQ},$ $\overrightarrow{PR},$ and $\overrightarrow{PT},$ as defined below. Compute the ratio: \[\frac{PT^2 + QU^2 + RV^2 + SW^2}{PQ^2 + PR^2 + PT^2}.\]
4
81
1
math
Given that Vertex E of right triangle ABE (where ∠AEB = 90°) is in the interior of unit square ABCD. Let R be the region consisting of all points inside ABCD and outside triangle ABE whose distance from AD is between 1/4 and 1/2. What is the area of R?
\frac{1}{8}
71
7
math
If $10 + 9 + 8 \times 7 \div \square + 6 - 5 \times 4 - 3 \times 2 = 1$, then $\square=$ $\qquad$.
28
47
2
math
Given $p:\frac{2x}{x+1}<1$ is a necessary but not sufficient condition for $q:a \lt x \lt a+1$ to hold, solve for the range of the real number $a$.
[-1, 0]
50
6
math
Given that the moving circle $M$ is tangent to the line $y=2$ and externally tangent to the fixed circle $C$: $x^{2}+(y+3)^{2}=1$, find the equation of the trajectory of the center of the moving circle $M$.
x^{2}=-12y
59
8
math
Determine the value of $\sin 36^{\circ}\cos 6^{\circ}-\sin 54^{\circ}\cos 84^{\circ}$.
\frac{1}{2}
39
7
math
A circle intersects the line $l_1: x - 6y - 10 = 0$ at point P(4, -1) and the center of the circle lies on the line $l_2: 5x - 3y = 0$. (I) Find the equation of the circle; (II) Find the length of the shortest chord that the circle cuts off from lines passing through the origin.
2 \sqrt{3}
90
6
math
Determine the smallest natural number \( k \) such that for any \( a \in [0,1] \) and any \( n \in \mathbf{N}^{*} \), it always holds that \( a^{k} (1-a)^{n} < \frac{1}{(n+1)^{3}} \).
4
74
1
math
Points $D, E, F$ lie on circle $O$ such that the line tangent to $O$ at $D$ intersects ray $\overrightarrow{E F}$ at $P$. Given that $P D=4, P F=2$, and $\angle F P D=60^{\circ}$, determine the area of circle $O$.
12 \pi
75
4
math
Chewbacca has 25 pieces of cherry gum and 40 pieces of grape gum. Some of the pieces are in complete packs, while others are loose. Each complete pack has exactly \(y\) pieces of gum. If Chewbacca loses two packs of cherry gum, then the ratio of the number of pieces of cherry gum he has to the number of pieces of grape...
2.5
101
3
math
Two semicircles, each with radius \(\sqrt{2}\), are tangent to each other. If \( AB \parallel CD \), determine the length of segment \( AD \).
4\sqrt{2}
38
6
math
In the polar coordinate system, the polar equation of curve $C$ is given by $ρ=4 \sqrt {2}\sin (θ+ \dfrac {π}{4})$. Establish a Cartesian coordinate system with point $O$ as the origin and the non-negative half of the polar axis as the $x$-axis. The parametric equations of line $l$ are given by $ \begin{cases} x=-2+ \d...
33
197
2
math
Find the positive integer $n$ such that the least common multiple of $n$ and $n - 30$ is $n + 1320$ .
165
43
3
math
Given the area of a circle is doubled when its radius $r$ is increased by $n$, determine the relationship between $r$ and $n$.
n(\sqrt{2} + 1)
31
10
math
A cube with 4-inch edges is made using 64 cubes with 1-inch edges. Forty-eight of the smaller cubes are white and sixteen are black. If the sixteen black cubes are placed so that each face of the larger cube has two black cubes along one edge, calculate the fraction of the surface area of the larger cube that is white.
\frac{7}{8}
71
7
math
In a store, there are candies priced at 2 p. per kg and 3 p. per kg, with an equal total cost for each type. At what price should the mixture of these candies be sold so that the total cost remains the same?
2.40 \, \text{rubles per kg}
52
14
math
Find the integer $m$, $0 \le m \le 180$, such that $\cos m^\circ = \cos 1234^\circ$.
154
36
3
math
Given the function $f(x) = (m+1)x^{2} - (m-1)x + m-1$. $(1)$ Solve the inequality with respect to $x$: $f(x) \geq (m+1)x$; $(2)$ If the inequality $f(x) \geq 0$ holds for all $x \in [-\frac{1}{2}, \frac{1}{2}]$, find the range of values for $m$.
[1, +\infty)
103
8
math
Find the smallest prime number that can be expressed as the sum of five different prime numbers.
43
18
2
math
For integers a, b, c, and d the polynomial $p(x) =$ $ax^3 + bx^2 + cx + d$ satisfies $p(5) + p(25) = 1906$ . Find the minimum possible value for $|p(15)|$ .
47
73
2
math
Given an arithmetic sequence $\{a_{n}\}$ with a common difference $d > 0$, and $a_{1}⋅a_{6}=11$, $a_{3}+a_{4}=12$. 1. Find the general term formula of the sequence $\{a_{n}\}$. 2. Find the sum of the first $n$ terms, denoted as $T_{n}$, of the sequence $\{\frac{a_{n+1}-2a_{n}}{2^{n+1}}\}$.
\frac{2n+1}{2^{n+1}} - \frac{1}{2}
117
22
math
In a positive geometric sequence $\{a_{n}\}$, it is known that $a_{1}a_{2}a_{3}=4$, $a_{4}a_{5}a_{6}=8$, and $a_{n}a_{n+1}a_{n+2}=128$. Find the value of $n$.
16
76
2
math
Given the function $f(x)=\cos 2x+2\sin x$. (Ⅰ) Find the value of $f\left(-\frac{\pi}{6}\right)$; (Ⅱ) When $x \in \left[-\frac{\pi}{2}, \frac{\pi}{2}\right]$, find the maximum value of the function $f(x)$ and the corresponding value of $x$.
\frac{3}{2}
90
7
math
In $\triangle ABC$, given $BC=2$, $AC=\sqrt{7}$, $B=\dfrac{2\pi}{3}$, find the area of $\triangle ABC$.
\dfrac{\sqrt{3}}{2}
40
10
math
Let $g$ be a function defined by $g\left(\dfrac{x}{3}\right)=x^3-x^2+2x+3$. Find the sum of all values of $y$ for which $g(3y)=9$.
\frac{1}{3}
54
7
math
Given the line $l\_1$: $\begin{cases} x=t \\ y= \sqrt {3}t \end{cases}$ (where $t$ is a parameter), establish a rectangular coordinate system with the coordinate origin as the pole and the positive half of the $x$-axis as the polar axis. The circle $C\_1$ is defined as $ρ^{2}-2 \sqrt {3}ρ\cos θ-4ρ\sin θ+6=0$. 1. Find ...
\dfrac {\sqrt {3}}{4}
168
10
math
Calculate the value of $9.98^5$ using the binomial theorem.
99004
18
5
math
Given $S_n$ be the sum of the first $n$ terms of a positive sequence $\{ a_n \}$, given $a_1 = 2$ and $S_{n+1}(S_{n+1} - 2S_n + 1) = 3S_n(S_n + 1)$, find the value of $a_{100}$.
4 \times 3^{98}
82
9
math
Find all values of \( c \) for which the inequality \( a + \sqrt{b + c} > b + \sqrt{a + c} \) holds for any positive \( a \) and \( b \) with \( a > b \).
c = \frac{1}{4}
54
9
math
Let $S$ be the set of all natural numbers with the property: the sum of the biggest three divisors of number $n$ , different from $n$ , is bigger than $n$ . Determine the largest natural number $k$ , which divides any number from $S$ . (A natural number is a positive integer)
6
75
1
math
11 people were standing in line under the rain, each holding an umbrella. They stood so close together that the umbrellas touched each other. Once the rain stopped, people closed their umbrellas and maintained a distance of 50 cm between each other. By how many times did the length of the queue decrease? Assume people ...
2.2
85
3
math
Find all functions \( g(x) \) that satisfy the equation: \[ \sin x + \cos y = f(x) + f(y) + g(x) - g(y), \; x, y \in \mathbf{R} \]
g(x) = \frac{\sin x - \cos x}{2} + C
54
18
math
Given vectors $\overrightarrow{a}, \overrightarrow{b}$ that satisfy $|\overrightarrow{a}| = |\overrightarrow{b}| = 2$, and $\overrightarrow{a} \cdot (\overrightarrow{b} - \overrightarrow{a}) = -6$, find the angle between $\overrightarrow{a}$ and $\overrightarrow{b}$.
\frac{2\pi}{3}
78
9
math
In the Tenth Kingdom, there are 17 islands, each with 119 inhabitants. The inhabitants are divided into two castes: knights, who always tell the truth, and liars, who always lie. During a population census, each person was first asked, "Not including yourself, are there an equal number of knights and liars on your isla...
1013
165
4
math
Alice and Bob each arrive at a meeting at a random time between 12:00 and 1:00. If Alice arrives after Bob, what is the probability that Bob arrived before 12:30?
\frac{1}{4}
47
7
math
Find the largest natural number $n$ such that for all real numbers $a, b, c, d$ the following holds: $$ (n + 2)\sqrt{a^2 + b^2} + (n + 1)\sqrt{a^2 + c^2} + (n + 1)\sqrt{a^2 + d^2} \ge n(a + b + c + d) $$
2
96
1
math
The director of a marching band wishes to place the members into a formation that includes all of them and has no unfilled positions. If they are arranged in a square formation, there are 5 members left over. The director realizes that if he arranges the group in a formation with 7 more rows than columns, there are no ...
294
82
3
math
The quadratic $x^2 + 520x + 600$ can be written in the form $(x+b)^2+c$, where $b$ and $c$ are constants. What is $\frac{c}{b}$?
-258
52
4
math
Find the number of scalene triangles having all sides of integral lengths, at least one side even, and a perimeter less than 16.
6
29
1
math
Given that \\(\{a_n\}\) is a geometric sequence satisfying \\(a_1=2\), and \\(a_2\), \\(a_3+2\), \\(a_4\) form an arithmetic sequence. The sequence \\(\{b_n\}\) satisfies \\(b_1+ \frac{1}{2}b_2+ \frac{1}{3}b_3+\ldots+ \frac{1}{n}b_n=2n\) for all natural numbers \\(n\). \\((1)\\) Find the general formula for \\(\{a_n\}\...
S_{2n} = \frac{2^{2n+1} - 2}{3} - 2n
198
26
math
Given the function $f(x)=\cos x(\sin x- \sqrt {3}\cos x)+ \frac { \sqrt {3}}{2}$, where $x\in\mathbb{R}$. - (I) Find the smallest positive period of $f(x)$ and the intervals of monotonic increase; - (II) If the function $g(x)=f(x+a)$ is even, find the minimum value of $|a|$.
\frac {\pi}{12}
96
8
math
Suppose nine circles of radius 1 are centered at every integer coordinate point within the square defined by vertices (0,0), (0,3), (3,0), and (3,3) in the first quadrant of the coordinate plane. Let $\mathcal{S}$ be the union of these circular regions. Line $m$, with slope 2, divides region $\mathcal{S}$ into two regi...
5
143
1
math
Given a sequence $\left\{ a_n \right\}$ that satisfies for any $n\in N^{*}$, we have $a_1^3+a_2^3+\cdots +a_n^3=(a_1+a_2+\cdots +a_n)^2$, and $a_n > 0$. (1) Find the general formula for the sequence $\left\{ a_n \right\}$. (2) Let the sum of the first $n$ terms of the sequence $\left\{ \frac{1}{a_n\cdot a_{n+2}} \...
(0, \frac{1}{2})
176
10
math
Given a triangle $\triangle ABC$ with the equations of the lines containing two of its altitudes being $2x - 3y + 1 = 0$ and $x + y = 0$, and the coordinates of vertex $A$ being $(1,2)$, find the equation of the line containing side $BC$.
2x + 3y + 7 = 0
69
12
math
Describe a regular octahedron around a sphere of radius \( R \) and find its volume.
4R^3 \sqrt{3}
21
9
math
Arc $AC$ is a quarter-circle with center $B$. The shaded region $ABC$ is "rolled" along another quarter-circle path $PQ$ (with the same radius as $AC$) until it reaches its original orientation for the first time with point $B$ landing at point $B^{\prime}$. If $BC = \frac{4}{\pi}$ cm, what is the length of the path th...
8\text{ cm}
102
6
math
Point $ A$ lies at $ (0, 4)$ and point $ B$ lies at $ (3, 8)$ . Find the $ x$ -coordinate of the point $ X$ on the $ x$ -axis maximizing $ \angle AXB$ .
5\sqrt{2} - 3
69
9
math
Compute $11^{-1} \pmod{1021}$. Express your answer as a residue from $0$ to $1020$, inclusive.
557
36
3
math
Let $n \geq 3$ be a positive integer. Find the maximum number of diagonals in a regular $n$ -gon one can select, so that any two of them do not intersect in the interior or they are perpendicular to each other.
n-3
56
3
math
In the polar coordinate system, the coordinates of point $P$ is $(1,0)$, and the equation of curve $C$ is $\rho =2\sqrt{2}\cos (\theta -\dfrac{\pi }{4})$. Establish a rectangular coordinate system with the pole as the coordinate origin and the positive semi-axis of the polar axis as the $x$-axis. A line $l$ with a slop...
|PA|^{2}+|PB|^{2}=4
170
14
math
A sequence of numbers \( t_{1}, t_{2}, t_{3}, \ldots \) has its terms defined by \( t_{n}=\frac{1}{n}-\frac{1}{n+2} \) for every integer \( n \geq 1 \). For example, \( t_{4}=\frac{1}{4}-\frac{1}{6} \). What is the largest positive integer \( k \) for which the sum of the first \( k \) terms (that is, \( t_{1}+t_{2}+\c...
1998
141
4
math
Given the one-variable quadratic equation $x^{2}+2x-(k-1)=0$, determine the range of values for $k$ such that the equation has real roots with respect to $x$.
k \geqslant 0
43
8
math
Find the range of values for $x$ such that $\frac{1}{x} < 3$ and $\frac{1}{x} > -2$, provided also that $2x - 5 > 0$. A) $x > \frac{5}{2}$ B) $x < -\frac{1}{2}$ C) $x < \frac{1}{3}$ D) $x < \frac{5}{2}$ E) $x > -\frac{1}{2}$
x > \frac{5}{2}
114
9
math
In triangle $\triangle ABC$, the sides opposite to angles $A$, $B$, and $C$ are $a$, $b$, and $c$ respectively, and $b\sin C = \sqrt{3}$, $\angle B = \frac{\pi}{4}$. $(1)$ Find the value of side $c$; $(2)$ If the area of $\triangle ABC$ is $\frac{9}{2}$, find the value of side $b$.
\sqrt{15}
101
6
math
A recent survey indicated that 70% of men and 75% of women endorse a new environmental policy. The survey included 200 men and 800 women. What percentage of the surveyed population supports the new policy?
74\%
50
4
math
Using only the digits $2,3$ and $9$ , how many six-digit numbers can be formed which are divisible by $6$ ?
81
34
2
math
Xiaoming is riding a bicycle, while Xiaoming's father is walking. They start from locations $A$ and $B$ respectively, moving towards each other. After meeting, Xiaoming continues for another 18 minutes to reach $B$. It is known that Xiaoming's cycling speed is 4 times that of his father's walking speed, and it takes Xi...
72
113
2
math
Let the function $y=f(x)$ have its first derivative $f'(x)$ and its second derivative $f''(x)$ on the interval $(a, b)$. If $f''(x)<0$ holds for all $x$ in $(a,b)$, then the function $f(x)$ is called a "convex function" on $(a,b)$. Given $f(x) = \frac{1}{12}x^4 - \frac{1}{6}mx^3 - \frac{3}{2}x^2$, (1) Find $f'(x)$ an...
b - a = 1 - (-1) = 2
225
13
math
Two pirates were playing with gold coins. First, the first pirate lost half of his coins (gave them to the second one), then the second pirate lost half of his coins, then the first pirate lost half of his coins again. As a result, the first pirate had 15 coins, and the second pirate had 33 coins. How many coins did th...
24
86
2
math
Find the integer $n$, $0 \le n \le 180$, such that $\cos n^\circ = \cos 812^\circ$.
92
35
2
math
We are allowed to remove exactly one integer from the list $$ -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 $$ and then we choose two distinct integers at random from the remaining list. What number should we remove if we wish to maximize the probability that the sum of the two chosen numbers is 12?
6
104
1
math
A set of composite numbers from the set $\{1,2,3,4, \ldots, 2016\}$ is called good if any two numbers in this set do not have common divisors (other than 1). What is the maximum number of numbers that a good set can have?
14
65
2
math
In a regular tetrahedron \( P-ABCD \) with lateral and base edge lengths both equal to 4, find the total length of all curve segments formed by a moving point on the surface at a distance of 3 from vertex \( P \).
6\pi
54
3
math
Triangle PQR has P=(0,0), R=(8,0), and Q in the first quadrant. Additionally, ∠QRP=90° and ∠QPR=45°. Determine the coordinates of the image of Q after P is rotated 120° counterclockwise about P.
(-4 - 4\sqrt{3}, 4\sqrt{3} - 4)
67
21
math
Given the lines $l_{1}$: $x+ay-a+2=0$ and $l_{2}$: $2ax+(a+3)y+a-5=0$. $(1)$ When $a=1$, find the coordinates of the intersection point of lines $l_{1}$ and $l_{2}$. $(2)$ If $l_{1}$ is parallel to $l_{2}$, find the value of $a$.
a = \frac{3}{2}
97
9
math
Compute the volumes of the bodies bounded by the surfaces: \[ z = 4x^2 + 9y^2 \] \[ z = 6 \]
3\pi
35
3
math
The domain of the function $f(x)=\frac{1}{\sqrt{1-\log_{2}x}}$ is (0, 2].
(0,2)
33
5
math
In a circle with center $O$ and radius $r$, chord $AB$ is drawn with length equal to $\sqrt{2}r$ units. From $O$, a perpendicular to $AB$ meets $AB$ at point $M$. From $M$, a perpendicular to $OA$ meets $OA$ at point $D$. What is the area of triangle $MDA$ expressed in terms of $r$? A) $\frac{3r^2}{16}$ B) $\frac{\pi r...
\frac{r^2}{4\sqrt{3}}
166
13
math
Given the line $y=x+1$ intersects with the ellipse $mx^2+my^2=1(m > n > 0)$ at points $A$ and $B$, where the x-coordinate of the midpoint of the chord $AB$ is equal to $-\frac{1}{3}$, find the eccentricity of the hyperbola $\frac{y^2}{m^2}-\frac{x^2}{n^2}=1$.
\frac{\sqrt{5}}{2}
96
10
math
Given the function $f(x)=A\sin (2x+\varphi)$ ($A > 0$, $0 < \varphi < \pi$), $x\in\mathbb{R}$ has a maximum value of $1$, and its graph passes through the point $M\left( \frac {\pi}{6}, \frac { \sqrt {3}}{2}\right)$. (I) Find $\varphi$; (II) Find the intervals of monotonic increase for $f(x)$; (III) Through what ...
\frac {\pi}{6}
140
7
math
It is desired to construct a right triangle in the coordinate plane so that its legs are parallel to the \( x \) and \( y \) axes and so that the medians to the midpoints of the legs lie on the lines \( y = 4x + 1 \) and \( y = nx + 2 \). Determine the number of different constants \( n \) for which such a triangle exi...
2
85
1
math
Five identical cylindrical pipes are stacked in a crate with two on the bottom and three resting on top of the first two. Each pipe has a diameter of $12\text{ cm}.$ Determine the height, $h,$ of this pile of $5$ pipes as shown below. [asy] draw(circle((10,10),12),black+linewidth(1)); draw(circle((30,10),12),black+lin...
12 + 6\sqrt{3}\text{ cm}
253
14
math
Given the sequence $\left\{a_{n}\right\}$ satisfies $a_{n+1}=\frac{3^{n+1} a_{n}}{a_{n}+3^{n+1}}, \, a_{1}=3$, find the general term of the sequence $\left\{a_{n}\right\}$.
\frac{2 \cdot 3^n}{3^n - 1}
74
16