Finding Antiderivatives and Indefinite Integrals

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AP Calculus AB › Finding Antiderivatives and Indefinite Integrals

Questions 1 - 10
1

A chemical amount changes at rate $A'(t)=\frac{1}{2}t^4-3t^2$. Which is an antiderivative of $A'(t)$?

$2t^3-6t$

$\frac{1}{10}t^5-t^3$

$\frac{1}{10}t^5-3t^2+C$

$\frac{1}{8}t^5-t^3+C$

$\frac{1}{10}t^5-t^3+C$

Explanation

This problem involves finding an antiderivative through fundamental integration principles. To find an antiderivative of A'(t) = (1/2)t⁴ - 3t², we apply the power rule: ∫tⁿ dt = t^(n+1)/(n+1) + C. For (1/2)t⁴, we get (1/2)·t⁵/5 = (1/10)t⁵, and for -3t², we get -3·t³/3 = -t³. Thus, the antiderivative is (1/10)t⁵ - t³ + C. Choice D ((1/10)t⁵ - 3t² + C) incorrectly integrates the second term, forgetting to increase the exponent—a mistake showing confusion about the integration process. Always remember: integration reverses differentiation by increasing powers and dividing by the new power.

2

A chemical amount changes at rate $A'(t)=4t^9+11$. Which expression is a general antiderivative of $A'(t)$?​

$\frac{2}{5}t^{10}+11t$

$\frac{2}{5}t^{10}+11t+C$

$\frac{4}{10}t^{10}+11t+C$

$\frac{4}{9}t^{10}+11t+C$

$4t^{10}+11t+C$

Explanation

This problem requires finding a general antiderivative of A'(t) = 4t⁹ + 11, demonstrating basic antiderivative reasoning. To find the antiderivative, we apply the power rule for integration: ∫tⁿdt = t^(n+1)/(n+1) + C. For 4t⁹, we get 4t¹⁰/10 = (2/5)t¹⁰; for the constant 11, we get 11t. Combining these terms with the constant of integration gives (2/5)t¹⁰ + 11t + C. Choice B ((4/10)t¹⁰ + 11t + C) shows the unsimplified fraction 4/10 instead of the reduced form 2/5, though both are mathematically equivalent. The key integration strategy is to apply the power rule carefully and simplify fractions when possible for cleaner expressions.

3

The marginal cost is $M(x)=12x^5+3x^2$. Which is an antiderivative of $M(x)$?

$2x^6+3x^3+C$

$2x^6+x^3+C$

$2x^6+x^3$

$60x^4+6x+C$

$12x^6+3x^3+C$

Explanation

This problem requires finding an antiderivative by applying the power rule for integration to each term. For M(x) = 12x⁵ + 3x², we integrate term by term: 12x⁵ becomes 12x⁶/6 = 2x⁶, and 3x² becomes 3x³/3 = x³. The antiderivative is 2x⁶ + x³ + C. Choice B (2x⁶ + 3x³ + C) incorrectly keeps the coefficient 3 when integrating 3x², failing to divide by the new exponent 3. Remember the integration formula: ∫axⁿ dx = axⁿ⁺¹/(n+1) + C, where you must divide by the new exponent to reverse the chain rule effect from differentiation.

4

The derivative of a function is $f'(x)=\frac{1}{2}x^7-6x$. Which is a general antiderivative of $f'(x)$?​

$\frac{1}{16}x^8-3x^2$

$\frac{1}{8}x^8-3x^2+C$

$\frac{1}{16}x^8-3x^2+C$

$\frac{7}{2}x^6-6$

$\frac{1}{16}x^8-6x^2+C$

Explanation

This problem asks for a general antiderivative of f'(x) = (1/2)x⁷ - 6x, testing basic antiderivative reasoning skills. To find the antiderivative, we apply the power rule for integration to each term separately. For (1/2)x⁷, we get (1/2)·x⁸/8 = x⁸/16; for -6x, we get -6x²/2 = -3x². Including the constant of integration yields (1/16)x⁸ - 3x² + C. Choice B ((1/16)x⁸ - 6x² + C) incorrectly integrates -6x as -6x² instead of -3x², failing to divide by the new exponent 2. The transferable strategy is to remember that when integrating axⁿ, the result is a·x^(n+1)/(n+1), requiring division by the new exponent.

5

A particle’s velocity is $v(t)=6t^2-4t+9$. Which function is an antiderivative of $v(t)$?

$2t^3-2t^2+9t+C$

$12t-4+9+C$

$6t^3-4t^2+9t+C$

$2t^3-4t^2+9t$

$2t^3-2t^2+9+C$

Explanation

This problem requires finding an antiderivative using basic integration rules. To find an antiderivative of v(t) = 6t² - 4t + 9, we reverse the differentiation process by applying the power rule for integration: ∫tⁿ dt = tⁿ⁺¹/(n+1) + C. For 6t², we get 6t³/3 = 2t³; for -4t, we get -4t²/2 = -2t²; and for 9, we get 9t. Combining these terms gives 2t³ - 2t² + 9t + C. Choice E (2t³ - 2t² + 9 + C) incorrectly integrates the constant 9 as 9 instead of 9t, forgetting that the integral of a constant is that constant times the variable. Remember: to verify an antiderivative, differentiate your answer and check if you get back the original function.

6

A function has derivative $g'(x)=3x^8-10x^4+2$. Which is a general antiderivative of $g'(x)$?​

$\frac{1}{3}x^9-2x^5+2x+C$

$24x^7-40x^3$

$3x^9-2x^5+2x+C$

$\frac{1}{9}x^9-2x^5+2x+C$

$\frac{1}{3}x^9-2x^5+2x$

Explanation

This problem asks for a general antiderivative of g'(x) = 3x⁸ - 10x⁴ + 2, testing basic antiderivative reasoning skills. To find the antiderivative, we apply the power rule for integration to each term. For 3x⁸, we get 3x⁹/9 = (1/3)x⁹; for -10x⁴, we get -10x⁵/5 = -2x⁵; for the constant 2, we get 2x. Combining these with the constant of integration yields (1/3)x⁹ - 2x⁵ + 2x + C. Choice D ((1/9)x⁹ - 2x⁵ + 2x + C) incorrectly integrates 3x⁸ as (1/9)x⁹ instead of (1/3)x⁹, making an error in simplifying 3/9. The transferable strategy is to carefully simplify coefficients after applying the power rule: when integrating $ax^n$, the result is a/(n+1)·x^(n+1).

7

A runner’s velocity is $v(t)=\dfrac{3}{2}t^4-5t$. Which is an antiderivative of $v(t)$?

$\dfrac{3}{8}t^5-\dfrac{5}{2}t^2+C$

$\dfrac{3}{10}t^5-5t^2+C$

$\dfrac{3}{10}t^5-\dfrac{5}{2}t^2+C$

$\dfrac{3}{2}t^5-\dfrac{5}{2}t^2+C$

$\dfrac{3}{10}t^5-\dfrac{5}{2}t^2$

Explanation

Finding antiderivatives requires careful application of the power rule, especially with fractional coefficients. To integrate v(t) = (3/2)t⁴ - 5t, we apply the rule to each term: (3/2)t⁴ becomes (3/2)t⁵/5 = (3/10)t⁵, and -5t becomes -5t²/2 = -(5/2)t². The antiderivative is (3/10)t⁵ - (5/2)t² + C. Choice E ((3/2)t⁵ - (5/2)t² + C) incorrectly keeps the original coefficient 3/2 when integrating (3/2)t⁴, forgetting to divide by the new exponent 5. When integrating terms with fractions, multiply the coefficient by 1/(n+1), which often creates more complex fractions that must be simplified.

8

The marginal cost is $C'(x)=9x^2+7x^6$. Which is a general antiderivative for $C'(x)$?​

$9x^3+7x^7+C$

$3x^3+x^7+C$

$3x^3+7x^7+C$

$3x^3+x^7$

$18x+42x^5$

Explanation

This problem asks for a general antiderivative of the marginal cost function C'(x) = 9x² + 7x⁶, testing basic antiderivative reasoning skills. To find the antiderivative, we apply the power rule for integration: for xⁿ, the antiderivative is x^(n+1)/(n+1). For 9x², we get 9x³/3 = 3x³; for 7x⁶, we get 7x⁷/7 = x⁷. Including the constant of integration, the general antiderivative is 3x³ + x⁷ + C. Choice D (3x³ + x⁷) omits the crucial constant of integration C, which represents all possible vertical translations of the antiderivative function. The transferable strategy is to always include +C in indefinite integrals, as this constant captures the infinite family of functions that all have the same derivative.

9

A population grows at rate $P'(t)=12t^5-5t^2$. Find an antiderivative of $P'(t)$.​

$2t^6-\frac{5}{3}t^3$

$2t^6-\frac{5}{3}t^3+C$

$60t^4-10t$

$2t^6-5t^3+C$

$12t^6-5t^3+C$

Explanation

This problem requires finding an antiderivative of the population growth rate P'(t) = 12t⁵ - 5t², demonstrating basic antiderivative reasoning. To find the antiderivative, we reverse the differentiation process using the power rule for integration. For 12t⁵, we get 12t⁶/6 = 2t⁶; for -5t², we get -5t³/3 = -5/3·t³. Combining these with the constant of integration gives 2t⁶ - (5/3)t³ + C. Choice B (2t⁶ - 5t³ + C) incorrectly integrates -5t² as -5t³ instead of -(5/3)t³, forgetting to divide by the new exponent. The key integration strategy is to carefully apply the power rule formula ∫tⁿdt = t^(n+1)/(n+1) + C, ensuring you divide by the new exponent (n+1).

10

A machine’s power usage rate is $p(t)=7t^2+14t^5$. Find $\int p(t),dt$.​

$14t+70t^4$

$\frac{7}{2}t^3+\frac{7}{3}t^6+C$

$\frac{7}{3}t^3+\frac{14}{6}t^6+C$

$\frac{7}{3}t^3+\frac{7}{3}t^6$

$\frac{7}{3}t^3+\frac{7}{3}t^6+C$

Explanation

This problem requires finding ∫p(t)dt where p(t) = 7t² + 14t⁵, demonstrating basic antiderivative reasoning through integration notation. To find the indefinite integral, we apply the power rule to each term: ∫tⁿdt = t^(n+1)/(n+1) + C. For 7t², we get 7t³/3 = (7/3)t³; for 14t⁵, we get 14t⁶/6 = (14/6)t⁶ = (7/3)t⁶. Including the constant of integration gives (7/3)t³ + (7/3)t⁶ + C. Choice B shows (14/6)t⁶ instead of the simplified (7/3)t⁶, though both are equivalent since 14/6 = 7/3. The key strategy is to simplify fractions in your final answer and always include +C for indefinite integrals.

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