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895
Let these numbers be A and B. Let B be the smallest of these numbers. Then the greater number is $A=10B+n$, where $n$ is the crossed-out digit, and $0 \leq n \leq 9$. According to the condition, $A+B = 11B + n = 2022$. Hence, $n$ is the remainder when 2022 is divided by 11, giving $n = 9$. We get $B = 183$ and $A = 183...
\mathrm{B}=183, \mathrm{~A}=1839
math
123
Given $w$ and $z$ are complex numbers such that $|w+z|=2$ and $|w^2+z^2|=20$, find the smallest possible value of $|w^3+z^3|$.
56
math
49
Solve the following equations using appropriate methods:<br/>$(1)x^{2}-2x-4=0$;<br/>$(2)x\left(x-2\right)+x-2=0$.
x_{1} = -1, \, x_{2} = 2
math
44
A rectangular prism has six faces, twelve edges, and eight vertices. A segment, such as $x$, which joins two vertices not joined by an edge, is called a diagonal. Considering the rectanglular prism has dimensions such that the length, height, and width are all different, calculate how many total diagonals it has and ho...
16
math
79
What is the modular inverse of $7$, modulo $800$? Express your answer as an integer from $0$ to $799$, inclusive.
343
math
34
Let $m=\underbrace{55555555}_{\text{8 digits}}$ and $n=\underbrace{111111111}_{\text{9 digits}}$. What is $\gcd(m,n)$?
1
math
56
Given the parabola $y=2x^2$, determine the coordinates of its focus.
\left(0, \frac{1}{8}\right)
math
20
A number $x$ is randomly chosen from the interval $[0,π]$. What is the probability that the event $\sin x + \sqrt{3} \cos x \leqslant 1$ occurs?
p = \frac{1}{2}
math
47
Find the distance from the center of the circle $(x+1)^{2}+y^{2}=2$ to the line $y=2x+3$.
\frac{\sqrt{5}}{5}
math
35
Which of the following statements are correct? Select the correct numbers. $(1)$ A right triangle has only one altitude. $(2)$ An $n$-sided polygon has a total of $n(n-3)$ diagonals. $(3)$ Two circles with equal radii are congruent. $(4)$ If a polygon has all sides equal, then it is a regular polygon. $(5)$ A...
(3), (5)
math
107
$DEB$ is a chord of a circle such that $DE=3$ and $EB=5$ . Let $O$ be the centre of the circle. Join $OE$ and extend $OE$ to cut the circle at $C$ . (See diagram). Given $EC=1$ , find the radius of the circle. [asy] size(6cm); pair O = (0,0), B = dir(110), D = dir(30), E = 0.4 * B + 0.6 * D, C = intersec...
16
math
233
Tossing a pair of dice, let the number obtained on the first throw be $m$ and on the second throw be $n$. 1. Find the probability that $m+n$ is not greater than 4. 2. Find the probability that $m < n+2$.
\frac{13}{18}
math
60
Zibo barbecue is famous throughout China. A specialty barbecue restaurant hopes to make good profits during the National Day holiday. After calculation, the cost of lamb skewers is $3$ yuan per skewer. Drawing on past experience, if each skewer is sold for $10$ yuan, on average, they can sell 300 skewers per day. If th...
7 \text{ yuan}
math
194
If the three angles \(\alpha\), \(\beta\), and \(\gamma\) form an arithmetic sequence with a common difference of \(\frac{\pi}{3}\), then \(\tan \alpha \cdot \tan \beta + \tan \beta \cdot \tan \gamma + \tan \gamma \cdot \tan \alpha =\) .
-3
math
74
For how many values of the digit $A$ is it true that $54$ is divisible by $A$ and $273{,}1A4$ is divisible by $4$?
2
math
43
Let $a, b \in \mathbb{R}$, and $a \neq 1$. Suppose the odd function $f(x) = \lg \frac{1+ax}{1+x}$ is defined on the interval $(-b, b)$. $(1)$ Find the value of $a$; $(2)$ Determine the range of values for $b$; $(3)$ Solve the inequality $f(x) > 0$.
(-1,0)
math
97
In the rectangular coordinate system, if the equation \( m\left(x^{2}+y^{2}+2y+1\right)=(x-2y+3)^{2} \) represents an ellipse, determine the range of values for \( m \).
(5,+\infty)
math
56
If $f(x+1) = \frac{3}{3+x}$ for all $x>0$, then $2f(x) =$ A) $\frac{6}{2 + x}$ B) $\frac{6}{3 + x}$ C) $\frac{9}{2 + x}$ D) $\frac{9}{3 + x}$ E) $\frac{3}{2 + x}$
\frac{6}{2 + x}
math
90
Given a $9 \times 9$ chess board, we consider all the rectangles whose edges lie along grid lines (the board consists of 81 unit squares, and the grid lines lie on the borders of the unit squares). For each such rectangle, we put a mark in every one of the unit squares inside it. When this process is completed, how man...
56
math
84
Calculate the coefficient of $x^{\frac{3}{2}}$ in the expansion of $\left(2x^2 - \dfrac{3}{x}\right)^9$.
0
math
39
If $e^{i \phi} = \frac{3 + i \sqrt{8}}{5},$ then find $\sin 4 \phi.$
\frac{12\sqrt{8}}{625}
math
33
The solution of the equation $7^{x+7} = 8^x$ can be expressed in the form $x = \log_b 7^7$. What is $b$?
\frac{8}{7}
math
41
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
math
59
Simply the expression \[\frac{(\sqrt{2} - 1)^{1 - \sqrt{3}}}{(\sqrt{2} + 1)^{1 + \sqrt{3}}},\]writing your answer as $a - b \sqrt{c},$ where $a,$ $b,$ and $c$ are positive integers, and $c$ is not divisible by the square of a prime.
3 - 2 \sqrt{2}
math
89
Given that the line $l$ passing through point $A(3,1)$ is tangent to circle $C$: $x^{2}+y^{2}-4y-1=0$ at point $B$, find the value of $\overrightarrow{CA} \cdot \overrightarrow{CB}$.
\overrightarrow{CA} \cdot \overrightarrow{CB} = 5
math
65
Let O be the origin of coordinates, C be the center of the circle $(x-2)^2+y^2=3$, and there is a point M$(x,y)$ on the circle satisfying $\overrightarrow{OM} \cdot \overrightarrow{CM} = 0$. Solve for the value of $\frac{y}{x}$.
\pm \sqrt{3}
math
72
Given that $F_1$ and $F_2$ are the common foci of an ellipse and a hyperbola, $P$ is their common point, and $\angle F_1 P F_2 = \frac{\pi}{3}$, find the minimum value of the product of the eccentricities of the ellipse and the hyperbola.
\frac{\sqrt{3}}{2}
math
74
An odd function $y=f\left(x\right)$ defined on $R$ satisfies $f\left(x+2\right)=-f\left(x\right)$. When $x\in \left(0,1\right]$, $f\left(x\right)=3^{x}-1$. Find $f\left(9.5\right)$.
\sqrt{3}-1
math
79
Find the roots of the polynomial \(6x^4 + 25x^3 - 59x^2 + 28x\). List your answers with rational numbers as fractions and irrational numbers in simplest radical form, separated by commas.
0, 1, \frac{-31 + \sqrt{1633}}{12}, \frac{-31 - \sqrt{1633}}{12}
math
52
Find the equation of the Apollonius Circle with foci at A(-2, 0) and B(2, 0), given that the moving point maintains a constant ratio λ = 1/2 to the distances from these foci.
x^2+y^2+\frac{20}{3}x+4=0
math
52
When a certain biased coin is flipped six times, the probability of getting heads exactly twice is equal to that of getting heads exactly three times. Let $\frac{i}{j}$, in lowest terms, be the probability that the coin comes up heads in exactly $4$ out of $6$ flips. Find $i+j$.
137089
math
66
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 \[ \frac{1}{a + \omega} + \frac{1}{b + \omega} + \frac{1}{c + \omega} + \frac{1}{d + \omega} = \frac{4}{\omega^2}, \] then find \[ \frac{1}{a + 1} + \frac{1}{b ...
4
math
165
In how many ways, can we draw $n-3$ diagonals of a $n$ -gon with equal sides and equal angles such that: $i)$ none of them intersect each other in the polygonal. $ii)$ each of the produced triangles has at least one common side with the polygonal.
\frac{1}{n-1} \binom{2n-4}{n-2}
math
69
A circle having radius \( r_1 \) centered at point \( N \) is tangent to a circle of radius \( r_2 \) centered at \( M \). Let \( l \) and \( j \) be the two common external tangent lines to the two circles. A circle centered at \( P \) with radius \( r_2 \) is externally tangent to circle \( N \) at the point at which...
3
math
169
Given the complex number $z= \frac{2}{1-i}$ (where $i$ is the imaginary unit), find the conjugate of the complex number $z$.
1 - i
math
36
How many four-character license plates consist of a consonant, followed by a vowel, followed by a consonant, and then a digit? (For this problem, consider Y a vowel.)
24{,}000
math
38
Given that the terminal side of angle $α$ passes through point $P$ with coordinates $\left(\sin \frac{2π}{3},\cos \frac{2π}{3}\right)$, determine the smallest positive value of angle $α$.
\dfrac{11π}{6}
math
53
Calculate the limit of the function: $$\lim _{x \rightarrow \frac{\pi}{2}}(\sin x)^{\frac{18 \sin x}{\operatorname{ctg} x}}$$
1
math
45
A sequence of positive integers is formed by removing all perfect squares from the sequence $1, 2, 3, ...$. What is the $2018^{\text{th}}$ term in this new sequence?
2063
math
47
Given vectors $\overrightarrow {a}$ = (cos($\frac {π}{3}$ - x), -sin(x)) and $\overrightarrow {b}$ = (sin(x + $\frac {π}{6}$), sin(x)), and a function f(x) = $\overrightarrow {a}$ • $\overrightarrow {b}$: (I) Find the smallest positive period and the monotonically decreasing interval of function f(x); (II) In triangle ...
\sqrt {3}
math
136
The sequence $\{a_{n}\}$ satisfies: $a_{1}=\frac{1}{4}$, $a_{2}=\frac{1}{5}$, and $a_{1}a_{2} + a_{2}a_{3} + \cdots + a_{n}a_{n+1} = n a_{1}a_{n+1}$ for any positive integer $n$. Then, find the value of $\frac{1}{a_{1}} + \frac{1}{a_{2}} + \cdots + \frac{1}{a_{97}}$.
5044
math
131
Find the derivative. \[ y = \cos (\operatorname{ctg} 2) - \frac{1}{16} \cdot \frac{\cos^2 (8x)}{\sin (16x)} \]
\frac{1}{4 \sin^2(8x)}
math
49
Given the hyperbola $C$: $\frac{x^{2}}{a^{2}} - \frac{y^{2}}{b^{2}} = 1 (a > 0, b > 0)$ with eccentricity $e = \sqrt{3}$, and $b = \sqrt{2}$. (I) Find the equation of the hyperbola $C$; (II) If $P$ is a point on hyperbola $C$ with left and right foci $E$ and $F$, respectively, and $\overrightarrow{PE} \cdot \overrighta...
2
math
142
Given the letters in the word BANANA, find the number of distinguishable rearrangements in which all the vowels are at the end and in alphabetical order.
3
math
33
A circle with a radius of 3 is centered at point $A$. An equilateral triangle with a side length of 6 units also has one vertex at point $A$. Determine the difference between the area of the region that lies inside the circle but outside of the triangle and the area of the region that lies inside the triangle but outsi...
9\sqrt{3} - 9\pi
math
118
Given that the derivative of the function $f(x)$ at $x=1$ is $1$, calculate $\lim_{x\to 0} \frac{f(1-x)-f(1+x)}{5x}$.
-\frac{2}{5}
math
49
Given a moving circle passing through a fixed point F(2, 0) and tangent to the line x = -2, determine the trajectory of the center C of the moving circle.
y^2 = 8x
math
38
What is the probability that when we roll five fair 6-sided dice, they won't all show the same number, and the numbers do not form a sequence?
\frac{7530}{7776}
math
33
Given a regular quadrilateral prism \(A B C D - A_{1} B_{1} C_{1} D_{1}\) with a base edge length of 2 and a lateral edge length of 4, where \(E\) is the midpoint of edge \(CD\) and \(F\) is the midpoint of edge \(AA_1\), find the distance from point \(D\) to plane \(EFB_1\).
\frac{2\sqrt{17}}{17}
math
90
The function $y=f(x-1)$ is an odd function, and $y=f(x+1)$ is an even function (both defined on $\mathbb{R}$). If $0 \leq x < 1$, then $f(x) = 2^x$. Find the value of $f(10)$.
1
math
70
(2009) Define a function $f(x)$ on $\mathbb{R}$ that satisfies $f(2+x) = f(2-x)$. If the equation $f(x) = 0$ has exactly three distinct real roots, and one of them is 0, then the other two roots of the equation $f(x) = 0$ are ____.
2, 4
math
80
Let \(a\), \(b\), and \(c\) be the lengths of the three sides of a triangle. Suppose \(a\) and \(b\) are the roots of the equation \[ x^2 + 4(c + 2) = (c + 4)x, \] and the largest angle of the triangle is \(x^\circ\). Find the value of \(x\).
90
math
84
Determine the values of $c$ for which $3$ is not in the range of the function $g(x) = x^2 + cx + 4$.
(-2, 2)
math
35
Given an odd function $y=f\left(x\right)$ defined on $R$, which is strictly decreasing on the interval $\left[0,+\infty \right)$. If for any $x\in R$, we always have $f(kx^{2}+2)+f\left(kx+k\right)\leqslant 0$ holds, then the range of real number $k$ is ______.
[0,+\infty)
math
89
Let $a = \pi/2008$. Find the smallest positive integer $n$ such that\[2[\cos(a)\sin(a) + \cos(4a)\sin(2a) + \cos(9a)\sin(3a) + \cdots + \cos(n^2a)\sin(na)]\]is an integer.
251
math
77
Given the function $f(x)=a\ln x$ ($a\in \mathbb{R}$). - (I) If the function $g(x)=2x+f(x)$ has a minimum value of $0$, find the value of $a$; - (II) Let $h(x)=f(x)+ax^{2}+(a^{2}+2)x$, find the monotonic intervals of the function $h(x)$; - (III) Suppose the function $y=f(x)$ and the function $u(x)= \frac {x-1}{2x}$ have...
\frac {1}{2}
math
161
Given a hexagon with certain angles given as $135^\circ$, $105^\circ$, $87^\circ$, $120^\circ$, and $78^\circ$, what is the measure of the unknown angle $Q$?
195^\circ
math
55
Given a pasture has 10 cows, which were infected due to accidentally consuming feed containing a virus, and the incidence rate of the disease is 0.02, let the number of cows that fall ill be denoted by ξ, then calculate Dξ.
0.196
math
55
Compute the definite integral: $$ \int_{1 / 24}^{1 / 3} \frac{5 \sqrt{x+1}}{(x+1)^{2} \sqrt{x}} \, dx $$
3
math
50
Given $x = \dfrac{1+i\sqrt{3}}{2}$, where $i = \sqrt{-1}$, calculate $\dfrac{1}{x^2 + x}$.
\frac{-i\sqrt{3}}{3}
math
43
A box contains 28 red balls, 20 green balls, 19 yellow balls, 13 blue balls, 11 white balls, and 9 black balls. Calculate the minimum number of balls that must be drawn from the box without replacement to guarantee that at least 15 balls of a single color will be drawn.
76
math
71
A book has 525 pages. Aunt Wang plans to read 25 pages every day, and it will take her     days to finish. If she reads 21 pages every day, it will take her     days to finish.
21, 25
math
54
$(1)$ If $x-y=3$ and $xy=2$, find the value of $x^{2}+y^{2}$;<br/>$(2)$ If $a$ satisfies $\left(4-a\right)^{2}+\left(a+3\right)^{2}=7$, find the value of $\left(4-a\right)\left(a+3\right)$.
21
math
85
Given $a$ is a real number, and $a^3 + 3a^2 + 3a + 2 = 0$, find the value of $(a+1)^{2008} + (a+1)^{2009} + (a+1)^{2010}$.
1
math
71
Given a geometric sequence $\{a_n\}$ satisfies $a_1 + a_2 = 3$ and $a_2 + a_3 = 6$, calculate the value of $a_7$.
64
math
45
Given the complex number $\frac{2-bi}{1+2i}$, if its real part and imaginary part are additive inverses of each other, then the real number $b$ is equal to ( ).
-\frac{2}{3}
math
45
A person starts from a certain point, moves forward 20 meters, then turns 30 degrees to the right, moves forward another 20 meters, turns 30 degrees to the right again, and continues this pattern. How many meters has the person walked in total by the time they return to the starting point?
240 \text{ meters}
math
67
Given points $P(-3, 4)$ and $Q(5, y)$ in a coordinate plane, for what value of $y$ is the slope of the line through $P$ and $Q$ equal to $\frac{1}{2}$? Also, find the coordinates of the midpoint of line segment $PQ$.
(1, 6)
math
69
Given the product of the digits of a 3-digit positive integer equals 30, find the number of such integers.
12
math
25
In acute triangle $\triangle ABC$, $\sin A = \sin^2 B + \sin\left( \frac{\pi}{4} + B \right)\sin\left( \frac{\pi}{4} - B \right)$. (1) Find the value of angle $A$; (2) If $\overrightarrow{AB} \cdot \overrightarrow{AC} = 12$, find the area of $\triangle ABC$.
2\sqrt{3}
math
96
Given the function $f(x)=\sin (2x- \frac {\pi}{6})+2\cos ^{2}x-1$. (I) Find the intervals of increase for the function $f(x)$. (II) In $\triangle ABC$, $a$, $b$, and $c$ are the sides opposite angles $A$, $B$, and $C$ respectively, and $a=1$, $b+c=2$, $f(A)= \frac {1}{2}$, find the area of $\triangle ABC$.
\frac { \sqrt {3}}{4}
math
116
Find the one-millionth digit after the decimal point in the decimal representation of the fraction \(3 / 41\).
7
math
25
How many $n$-digit numbers can be written using the digits 1 and 2, where no two adjacent digits are both 1? Let the count of such $n$-digit numbers be denoted by $f(n)$. Find $f(10)$.
144
math
58
There are 20 cards numbered $1, 2, \cdots, 19, 20$. These cards are placed in a box, and 4 people each draw one card from the box. The two people who draw the two smaller numbers form one group, and the two people who draw the two larger numbers form another group. If two of the people draw the numbers 5 and 14, what i...
\frac{7}{51}
math
105
Given the function $f(x) = x^3 - 6x + 5, x \in \mathbb{R}$. (1) Find the equation of the tangent line to the function $f(x)$ at $x = 1$; (2) Find the extreme values of $f(x)$ in the interval $[-2, 2]$.
5 - 4\sqrt{2}
math
77
The solution set of the inequality $(x+3)(6-x) \geq 0$ is to be determined.
[-3,6]
math
25
Find $546_{8} - 321_{8} - 105_{8}$. Express your answer in base $8$.
120_8
math
33
Determine all pairs of non-negative integers \((n, k)\) such that \[ 2023 + 2^n = k^2 \]
(1, 45)
math
35
The function $g$ is given by the table \[\begin{tabular}{|c||c|c|c|c|c|c|} \hline x & 0 & 1 & 2 & 3 & 4 & 5 \\ \hline g(x) & 2 & 5 & 3 & 0 & 1 & 4 \\ \hline \end{tabular}\] If $v_0=0$ and $v_{n+1} = g(v_n)$ for $n \ge 0$, find $v_{2010}$. A) 0 B) 1 C) 2 D) 3 E) 4
\text{(A) } 0
math
160
In the trapezoid \(ABCD\), the side \(CD\) is equal to the diagonal \(AC\). On the smaller arc \(BC\) of the circumcircle of triangle \(BCD\), a point \(E\) is chosen such that \(CD = CE\). Find the angle \(\angle AEB\).
90^\circ
math
68
Given $g(x)=mx+2$ and $f(x)=x^{2}-2x$, if for all $x\_1\in[-1,2]$ there exists an $x\_0\in[-1,2]$ such that $g(x\_1)=f(x\_0)$ holds true, then the range of values for $m$ is _____.
[-1, \frac{1}{2}]
math
77
Two circles with radii 2 and 6, centered at points \( O_{1} \) and \( O_{2} \) respectively, are externally tangent at point \( C \). A common external tangent and a common internal tangent to the circles are drawn. These tangents intersect at point \( D \). Find the radius of the inscribed circle in triangle \( O_{1} ...
2(\sqrt{3} - 1)
math
87
The function $f(x)=2\sin (\omega x+ \frac {\pi}{6})$ ($\omega > 0$) is monotonically increasing on the interval $( \frac {\pi}{2},\pi)$. Determine the range of $\omega$.
(0, \frac {1}{3}]
math
56
The difference between the maximum and minimum values of the function $y=2\sin \left( \frac{\pi x}{6}-\frac{\pi }{3} \right)(0\leqslant x\leqslant 9)$ is ______.
2+ \sqrt{3}
math
57
Let a cube have a side length of $a$, with two parallel square faces labeled $A B C D$ and $E F G H$. Let $M$ be the center of the face $E F G H$. How far is the line $M A$ from the line $B C$?
\frac{2\sqrt{5}}{5} a
math
63
When selecting the first trial point using the 0.618 method during the process, if the experimental interval is $[2000, 3000]$, the first trial point $x_1$ should be chosen at ______.
2618
math
53
Given that $\overrightarrow {a}$, $\overrightarrow {b}$, $\overrightarrow {c}$ are three vectors in the same plane, where $\overrightarrow {a} = \left(1, \sqrt {3}\right)$. (I) If $|\overrightarrow {c}| = 4$ and $\overrightarrow {c}$ is parallel to $\overrightarrow {a}$, find the coordinates of $\overrightarrow {c}$. ...
\dfrac{\pi}{3}
math
172
In the sequence $\{a_n\}$, $a_1=1$, $a_{n+1}=a_n+2^n$ ($n\in\mathbb{N}^+$), then its general formula is.
a_n=2^n-1
math
49
Use the Horner's method (also known as Qin Jiushao algorithm) to compute the value of the polynomial: $f(x) = 2x^6 + 3x^5 + 5x^3 + 6x^2 + 7x + 1$ when $x = 0.5$. Determine the number of multiplication and addition operations required.
6
math
79
A family's telephone has the following probabilities of being answered: 0.1 for the first ring, 0.2 for the second ring, and 0.25 for both the third and fourth rings. Calculate the probability that the phone is answered before the fifth ring.
0.8
math
57
Suppose $b$ is an integer such that $0 \le b \le 20$, and $74639281_{85} - b$ is a multiple of $17$. What is $b$?
1
math
52
Given the following propositions: ① "a > b" is a sufficient but not necessary condition for "a<sup>2</sup> > b<sup>2</sup>"; ② "lga = lgb" is a necessary but not sufficient condition for "a = b"; ③ If x, y ∈ R, then "|x| = |y|" is a necessary and sufficient condition for "x<sup>2</sup> = y<sup>2</sup>"; ④ In △A...
③④
math
152
Given that the probability of a severe flood occurring within 30 years is 0.8, the probability of occurring within 40 years is 0.85, and 30 years have passed without a severe flood in this region, calculate the probability of a severe flood occurring in this region in the next 10 years.
0.25
math
70
Suppose $A$, $B$, and $C$ are sets such that $|A| = 7$, $|B| = 7$, and $|C| = 6$. If $n(A) + n(B) + n(C) = n(A \cup B \cup C)$, find the minimum possible value of $|A \cap B \cap C|$.
1
math
82
Find all pairs of prime numbers $(p, q)$ such that $pq \mid \left(p^{p} + q^{q} + 1\right)$.
(2, 5) \text{ or } (5, 2)
math
35
The sequence $\left\{a_{n}\right\}$ is defined by the conditions $a_{1}=1$ and $a_{n}=a_{1}+a_{2}+\ldots+a_{n-1}+n$ for $n \geqslant 2$. Find the explicit formula for this sequence.
a_n = 2^n - 1
math
71
Five plastic bottles are required to make a new bottle. How many new bottles can eventually be made from 625 plastic bottles, assuming that at least three bottles are needed to start a recycling process? Do not include the original 625 bottles in your count.
156
math
55
Convert $1024_{10}$ to base 8.
2000_8
math
15
Solve the equation \( x'' - 5x' + 4x = 4 \) with initial conditions \( x(0) = 0 \) and \( x'(0) = 2 \).
x(t) = 1 - 2e^t + e^{4t}
math
45
We are fitting new tires on both wheels of a motorcycle. A tire is considered completely worn out if it has run $15000 \mathrm{~km}$ on the rear wheel or $25000 \mathrm{~km}$ on the front wheel. What is the maximum distance the motorcycle can travel until the tires are completely worn out, if we exchange the front tire...
18750 \text{ km}
math
89