Selecting Procedures for Calculating Derivatives

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AP Calculus AB › Selecting Procedures for Calculating Derivatives

Questions 1 - 10
1

A particle’s position is $s(t)=(t^2+1)^{7/2}$. Which differentiation rule is used to determine $s'(t)$?

Chain rule

Implicit differentiation

Quotient rule

Logarithmic differentiation is required

Product rule

Explanation

This problem requires selecting the appropriate differentiation procedure for $s(t)=(t^2+1)^{7/2}$. This function is a composite where the outer function is a power function with exponent $7/2$ and the inner function is $t^2+1$. The chain rule is necessary to handle this composition properly. The product rule doesn't apply since there's no multiplication of separate functions, and the quotient rule isn't needed since there's no division. Logarithmic differentiation could be used but isn't required for this straightforward power composition. When you see a function raised to a power where the base is not simply $x$, the chain rule is typically the most direct approach.

2

A revenue function is $R(x)=e^{2x},(x^4+1)$. Which differentiation rules are needed to find $R'(x)$?

Quotient rule and chain rule

Product rule only

Implicit differentiation

Chain rule only

Product rule and chain rule

Explanation

This problem requires selecting differentiation procedures for the revenue function $R(x)=e^{2x},(x^4+1)$. This is a product of two functions: $e^{2x}$ and $(x^4+1)$, so the product rule is necessary. Additionally, the first factor $e^{2x}$ is a composite function where the outer function is the exponential and the inner function is $2x$, requiring the chain rule for proper differentiation. The quotient rule doesn't apply since this isn't a fraction, and implicit differentiation isn't needed for this explicit function. When you see a product where one factor is an exponential with a non-trivial exponent, expect to use both product rule and chain rule.

3

Given $p(x)=\tan(5x),\cos(x^2)$, which differentiation rules should be used to find $p'(x)$?

Chain rule only

Quotient rule only

Implicit differentiation

Product rule and chain rule

Power rule only

Explanation

This problem requires selecting differentiation procedures for $p(x)=\tan(5x),\cos(x^2)$. This function is a product of two trigonometric functions, so the product rule is necessary. Additionally, both factors are composite functions: $\tan(5x)$ has inner function $5x$, and $\cos(x^2)$ has inner function $x^2$, both requiring the chain rule for proper differentiation. The quotient rule doesn't apply since this is a product, not a quotient, and implicit differentiation isn't needed for this explicit function. When you see a product of trigonometric functions with non-trivial arguments, expect to use both product rule and chain rule.

4

A population is modeled by $P(t)=\dfrac{t^2+3t}{\ln(t+1)}$. Which differentiation rule(s) should be used to compute $P'(t)$?

Quotient rule and chain rule

Chain rule only

Power rule only

Logarithmic differentiation (taking $\ln$ of both sides) is required

Product rule only

Explanation

This problem requires selecting appropriate differentiation procedures for $P(t)=\dfrac{t^2+3t}{\ln(t+1)}$. Since this is a fraction with both numerator and denominator being functions of $t$, the quotient rule is necessary. Additionally, the denominator $\ln(t+1)$ is a composite function requiring the chain rule to differentiate properly. The product rule alone wouldn't work since this is a quotient, and the power rule is insufficient for handling the logarithmic denominator. Logarithmic differentiation is not required here as we can directly apply the quotient rule. When you see a fraction where the denominator contains a composite function, expect to use both quotient rule and chain rule.

5

Given $f(x)=\sin!ig((3x-2)^5\big)$, which differentiation procedure is appropriate for finding $f'(x)$?

Product rule and chain rule

Power rule only

Quotient rule

Implicit differentiation

Chain rule (with the derivative of $\sin$)

Explanation

This problem involves selecting procedures for differentiating $f(x)=\sin!\big((3x-2)^5\big)$. This function is a composition where the outer function is sine and the inner function is $(3x-2)^5$. The chain rule is required to handle this composite structure, and we need the derivative of sine as well. The product rule doesn't apply since there's no multiplication of separate functions, and the quotient rule isn't needed since there's no division. Implicit differentiation isn't required as this is an explicit function. When you encounter a trigonometric function with a composite argument, the chain rule with the appropriate trigonometric derivative is the correct approach.

6

For $r(x)=\dfrac{(x^2+1)^5}{x^3}$, which differentiation rules are required to find $r'(x)$?

Chain rule only

No rules beyond the quotient rule are possible

Power rule only

Implicit differentiation only

Product rule and chain rule (rewrite as a product with $x^{-3}$)

Explanation

This problem requires selecting differentiation procedures for $r(x)=\dfrac{(x^2+1)^5}{x^3}$. While the quotient rule could be applied directly, it's more efficient to rewrite this as $r(x)=(x^2+1)^5 \cdot x^{-3}$ and use the product rule combined with the chain rule. The term $(x^2+1)^5$ requires the chain rule (outer function is the 5th power, inner function is $x^2+1$), and $x^{-3}$ differentiates using the power rule. This approach avoids the complexity of applying the quotient rule to expressions with high powers. When you have a quotient where the numerator contains a composite function, consider rewriting as a product with negative exponents.

7

A function is $H(x)=\sqrt{x},e^{x^2}$. Which differentiation rules are needed to find $H'(x)$?

Quotient rule only

Product rule and chain rule

Implicit differentiation

Chain rule only

Power rule only

Explanation

This problem requires selecting differentiation procedures for $H(x)=\sqrt{x},e^{x^2}$. This function is a product of two functions: $\sqrt{x}$ and $e^{x^2}$, so the product rule is necessary. Additionally, the second factor $e^{x^2}$ is a composite function where the outer function is the exponential and the inner function is $x^2$, requiring the chain rule. The first factor $\sqrt{x} = x^{1/2}$ differentiates using the power rule. The quotient rule doesn't apply since this is a product, and implicit differentiation isn't needed. When you encounter a product where one factor is a composite exponential function, expect to use both product rule and chain rule.

8

Let $y$ be defined by $e^{y}+xy=4$. Which differentiation procedure is needed to find $\dfrac{dy}{dx}$?

Chain rule only on an explicit function

Quotient rule

Power rule only

Implicit differentiation (including product rule on $xy$)

Logarithmic differentiation

Explanation

This problem involves selecting the differentiation procedure for finding $\dfrac{dy}{dx}$ when $y$ is defined implicitly by $e^{y}+xy=4$. Since $y$ cannot be easily isolated as an explicit function of $x$, implicit differentiation is required. This involves differentiating both sides with respect to $x$, treating $y$ as a function of $x$. The term $e^y$ requires the chain rule (giving $e^y \frac{dy}{dx}$), and the term $xy$ requires the product rule (giving $y + x\frac{dy}{dx}$). Neither quotient rule alone nor explicit function methods apply to this implicit relationship. When you have an equation mixing $x$ and $y$ terms where $y$ cannot be isolated, implicit differentiation with appropriate subsidiary rules is necessary.

9

For $G(x)=\dfrac{e^{x}}{\sqrt{x^2+9}}$, which differentiation rules should be used to compute $G'(x)$?

Chain rule only

Quotient rule and chain rule

Power rule only

No rule beyond product rule is needed

Implicit differentiation

Explanation

This problem requires selecting differentiation procedures for $G(x)=\dfrac{e^{x}}{\sqrt{x^2+9}}$. Since this is a quotient, the quotient rule is necessary. Additionally, the denominator $\sqrt{x^2+9}$ is a composite function where the outer function is the square root and the inner function is $x^2+9$, requiring the chain rule when differentiating the denominator. The numerator $e^x$ differentiates to itself. The product rule alone wouldn't work since this is a quotient structure, and implicit differentiation isn't needed for this explicit function. When you have a quotient where either part contains a composite function, combine the quotient rule with the chain rule.

10

For $u(x)=\sqrt{1-\sin x}$, which differentiation rules are required to find $u'(x)$?

Implicit differentiation

Product rule only

Power rule only

Chain rule applied twice

Quotient rule only

Explanation

This problem requires selecting differentiation procedures for $u(x)=\sqrt{1-\sin x}$. This function involves nested composition: the outer function is the square root, and the inner function is $1-\sin x$. The chain rule must be applied twice - first for the square root, then for the sine function within the expression $1-\sin x$. Working from outside to inside: the derivative of $\sqrt{u}$ is $\frac{1}{2\sqrt{u}}$, and then we need the derivative of $1-\sin x$, which is $-\cos x$. The product rule doesn't apply since this is a single composite function, and implicit differentiation isn't needed. When you encounter functions with multiple layers of composition, apply the chain rule repeatedly, working from the outermost function inward.

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