China Mathematical Olympiad

Description: China Mathematical Olympiad is a prestigious mathematics competition for high school students in China. It is held annually and is one of the most challenging mathematics competitions in the world.
Number of Questions: 14
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Tags: mathematics mathematical competitions china mathematical olympiad
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What is the value of x in the equation (x^2 + 2x - 3 = 0)?

  1. -1

  2. 1

  3. 2

  4. 3


Correct Option: B
Explanation:

To solve the equation (x^2 + 2x - 3 = 0), we can use the quadratic formula: (x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}). Substituting the values of a, b, and c into the formula, we get: (x = \frac{-2 \pm \sqrt{2^2 - 4(1)(-3)}}{2(1)}) = \frac{-2 \pm \sqrt{4 + 12}}{2} = \frac{-2 \pm \sqrt{16}}{2} = \frac{-2 \pm 4}{2} = 1 or -3). Therefore, the value of x is 1.

What is the area of a triangle with sides of length 3, 4, and 5?

  1. 6

  2. 8

  3. 10

  4. 12


Correct Option: A
Explanation:

To find the area of a triangle with sides of length 3, 4, and 5, we can use Heron's formula: (Area = \sqrt{s(s-a)(s-b)(s-c)}), where s is the semiperimeter of the triangle. The semiperimeter is (s = \frac{a + b + c}{2} = \frac{3 + 4 + 5}{2} = 6). Substituting the values of s, a, b, and c into the formula, we get: (Area = \sqrt{6(6-3)(6-4)(6-5)} = \sqrt{6 \cdot 3 \cdot 2 \cdot 1} = \sqrt{36} = 6). Therefore, the area of the triangle is 6.

What is the sum of the first 100 positive integers?

  1. 4950

  2. 5050

  3. 5150

  4. 5250


Correct Option: B
Explanation:

The sum of the first 100 positive integers can be found using the formula (S = \frac{n(n+1)}{2}), where n is the number of integers. Substituting n = 100 into the formula, we get: (S = \frac{100(100+1)}{2} = \frac{100 \cdot 101}{2} = 5050). Therefore, the sum of the first 100 positive integers is 5050.

What is the probability of getting a head when flipping a coin?

  1. 1/2

  2. 1/3

  3. 1/4

  4. 1/5


Correct Option: A
Explanation:

When flipping a coin, there are two possible outcomes: head or tail. Since each outcome is equally likely, the probability of getting a head is (1/2).

What is the volume of a sphere with radius 5?

  1. 125\pi

  2. 250\pi

  3. 375\pi

  4. 500\pi


Correct Option: C
Explanation:

The volume of a sphere with radius r is given by the formula (V = \frac{4}{3}\pi r^3). Substituting r = 5 into the formula, we get: (V = \frac{4}{3}\pi (5^3) = \frac{4}{3}\pi \cdot 125 = 375\pi). Therefore, the volume of the sphere is 375\pi.

What is the derivative of the function (f(x) = x^3 + 2x^2 - 3x + 4)?

  1. 3x^2 + 4x - 3

  2. 3x^2 + 4x + 3

  3. 3x^2 - 4x - 3

  4. 3x^2 - 4x + 3


Correct Option: A
Explanation:

The derivative of a function (f(x)) is given by the limit (\lim_{h \to 0} \frac{f(x+h) - f(x)}{h}). Applying this limit to the function (f(x) = x^3 + 2x^2 - 3x + 4), we get: (\lim_{h \to 0} \frac{(x+h)^3 + 2(x+h)^2 - 3(x+h) + 4 - (x^3 + 2x^2 - 3x + 4)}{h}) = (\lim_{h \to 0} \frac{x^3 + 3x^2h + 3xh^2 + h^3 + 2x^2 + 4xh + 2h^2 - 3x - 3h + 4 - x^3 - 2x^2 + 3x - 4}{h}) = (\lim_{h \to 0} \frac{3x^2h + 3xh^2 + h^3 + 4xh + 2h^2 - 3h}{h}) = (\lim_{h \to 0} \frac{h(3x^2 + 3xh + h^2 + 4x + 2h - 3)}{h}) = (\lim_{h \to 0} (3x^2 + 3xh + h^2 + 4x + 2h - 3)) = (3x^2 + 4x - 3). Therefore, the derivative of the function (f(x) = x^3 + 2x^2 - 3x + 4) is (3x^2 + 4x - 3).

What is the equation of the line that passes through the points ((2, 3)) and ((5, 7))?

  1. (y = 2x + 1)

  2. (y = 2x - 1)

  3. (y = x + 3)

  4. (y = x - 3)


Correct Option: A
Explanation:

The equation of a line that passes through two points ((x_1, y_1)) and ((x_2, y_2)) is given by the point-slope form: (y - y_1 = \frac{y_2 - y_1}{x_2 - x_1} (x - x_1)). Substituting the values of (x_1, y_1, x_2,) and (y_2) into the formula, we get: (y - 3 = \frac{7 - 3}{5 - 2} (x - 2)) = (y - 3 = \frac{4}{3} (x - 2)) = (y - 3 = \frac{4}{3}x - \frac{8}{3}) = (y = \frac{4}{3}x - \frac{8}{3} + 3) = (y = \frac{4}{3}x + 1). Therefore, the equation of the line that passes through the points ((2, 3)) and ((5, 7)) is (y = 2x + 1).

What is the value of the expression (\frac{1}{2} + \frac{1}{3} + \frac{1}{6})?

  1. 1

  2. 1.1

  3. 1.2

  4. 1.3


Correct Option: B
Explanation:

To evaluate the expression (\frac{1}{2} + \frac{1}{3} + \frac{1}{6}), we can find a common denominator: (\frac{1}{2} + \frac{1}{3} + \frac{1}{6} = \frac{3}{6} + \frac{2}{6} + \frac{1}{6} = \frac{6}{6} = 1). Therefore, the value of the expression is 1.1.

What is the smallest positive integer that is divisible by 2, 3, and 5?

  1. 15

  2. 30

  3. 45

  4. 60


Correct Option: B
Explanation:

The smallest positive integer that is divisible by 2, 3, and 5 is the least common multiple (LCM) of 2, 3, and 5. The prime factorization of 2 is (2), the prime factorization of 3 is (3), and the prime factorization of 5 is (5). Therefore, the LCM of 2, 3, and 5 is (2 \cdot 3 \cdot 5 = 30). Therefore, the smallest positive integer that is divisible by 2, 3, and 5 is 30.

What is the value of (\log_2 32)?

  1. 4

  2. 5

  3. 6

  4. 7


Correct Option: B
Explanation:

To evaluate (\log_2 32), we need to find the exponent to which 2 must be raised to get 32. We can write (32 = 2^x). Solving for x, we get: (x = \log_2 32). Therefore, the value of (\log_2 32) is 5.

What is the area of a regular hexagon with side length 6?

  1. 36\sqrt{3}

  2. 72\sqrt{3}

  3. 108\sqrt{3}

  4. 144\sqrt{3}


Correct Option: C
Explanation:

The area of a regular hexagon with side length s is given by the formula (A = \frac{3\sqrt{3}}{2}s^2). Substituting s = 6 into the formula, we get: (A = \frac{3\sqrt{3}}{2} \cdot 6^2 = \frac{3\sqrt{3}}{2} \cdot 36 = 108\sqrt{3}). Therefore, the area of the regular hexagon is 108\sqrt{3}.

What is the volume of a rectangular prism with length 8, width 5, and height 3?

  1. 120

  2. 150

  3. 180

  4. 210


Correct Option: A
Explanation:

The volume of a rectangular prism with length l, width w, and height h is given by the formula (V = lwh). Substituting l = 8, w = 5, and h = 3 into the formula, we get: (V = 8 \cdot 5 \cdot 3 = 120). Therefore, the volume of the rectangular prism is 120.

What is the probability of getting two heads when flipping two coins?

  1. 1/4

  2. 1/2

  3. 3/4

  4. 1


Correct Option: A
Explanation:

When flipping two coins, there are four possible outcomes: HH, HT, TH, and TT. Since each outcome is equally likely, the probability of getting two heads is (1/4).

What is the equation of the circle with center ((2, 3)) and radius 5?

  1. ((x - 2)^2 + (y - 3)^2 = 25)

  2. ((x - 2)^2 + (y - 3)^2 = 10)

  3. ((x - 2)^2 + (y - 3)^2 = 15)

  4. ((x - 2)^2 + (y - 3)^2 = 20)


Correct Option: A
Explanation:

The equation of a circle with center ((h, k)) and radius r is given by the formula ((x - h)^2 + (y - k)^2 = r^2). Substituting h = 2, k = 3, and r = 5 into the formula, we get: ((x - 2)^2 + (y - 3)^2 = 5^2) = ((x - 2)^2 + (y - 3)^2 = 25). Therefore, the equation of the circle with center ((2, 3)) and radius 5 is ((x - 2)^2 + (y - 3)^2 = 25).

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