Math Problem Statement

Given the following information about differentiable functions f(x) and g(x) at x = 2, determine the derivatives for the following cases: a) \( \frac{d}{dx} [f(g(x))] \) at \( x = 2 \) b) \( \frac{d}{dx} \left[ \frac{1}{f(x)} \right] \) at \( x = 2 \) c) \( \frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] \) at \( x = 2 \)

Solution

Let's solve each part step by step using the given table values and derivative rules.


Given Table:

xxf(x)f(x)g(x)g(x)f(x)f'(x)g(x)g'(x)
2288222π2\piee

At x=2x = 2:

  • f(2)=8f(2) = 8
  • g(2)=2g(2) = 2
  • f(2)=2πf'(2) = 2\pi
  • g(2)=eg'(2) = e

Part a: ddx[f(g(x))]\frac{d}{dx} [f(g(x))] at x=2x = 2

To solve this, we use the chain rule: ddx[f(g(x))]=f(g(x))g(x)\frac{d}{dx} [f(g(x))] = f'(g(x)) \cdot g'(x)

  1. At x=2x = 2, g(2)=2g(2) = 2, so f(g(2))=f(2)=2πf'(g(2)) = f'(2) = 2\pi.
  2. g(2)=eg'(2) = e.

Now multiply: ddx[f(g(x))]=f(g(2))g(2)=(2π)e=2πe\frac{d}{dx} [f(g(x))] = f'(g(2)) \cdot g'(2) = (2\pi) \cdot e = 2\pi e

Answer for Part a: 2πe2\pi e


Part b: ddx[1f(x)]\frac{d}{dx} \left[ \frac{1}{f(x)} \right] at x=2x = 2

To solve this, use the derivative of a reciprocal rule: ddx[1f(x)]=f(x)(f(x))2\frac{d}{dx} \left[ \frac{1}{f(x)} \right] = -\frac{f'(x)}{(f(x))^2}

  1. At x=2x = 2, f(2)=8f(2) = 8 and f(2)=2πf'(2) = 2\pi.

Substitute these values: ddx[1f(x)]=f(2)(f(2))2=2π(8)2\frac{d}{dx} \left[ \frac{1}{f(x)} \right] = -\frac{f'(2)}{(f(2))^2} = -\frac{2\pi}{(8)^2}

Simplify: ddx[1f(x)]=2π64=π32\frac{d}{dx} \left[ \frac{1}{f(x)} \right] = -\frac{2\pi}{64} = -\frac{\pi}{32}

Answer for Part b: π32-\frac{\pi}{32}


Part c: ddx[g(x)f(x)]\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] at x=2x = 2

To solve this, use the quotient rule: ddx[g(x)f(x)]=g(x)f(x)g(x)f(x)(f(x))2\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{g'(x)f(x) - g(x)f'(x)}{(f(x))^2}

  1. At x=2x = 2:
    • g(2)=2g(2) = 2, f(2)=8f(2) = 8,
    • g(2)=eg'(2) = e, f(2)=2πf'(2) = 2\pi.

Substitute these values: ddx[g(x)f(x)]=g(2)f(2)g(2)f(2)(f(2))2\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{g'(2)f(2) - g(2)f'(2)}{(f(2))^2} ddx[g(x)f(x)]=(e)(8)(2)(2π)(8)2\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{(e)(8) - (2)(2\pi)}{(8)^2}

Simplify the numerator: (e)(8)(2)(2π)=8e4π(e)(8) - (2)(2\pi) = 8e - 4\pi

Simplify the denominator: (8)2=64(8)^2 = 64

Thus: ddx[g(x)f(x)]=8e4π64\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{8e - 4\pi}{64}

Simplify further: ddx[g(x)f(x)]=8e644π64=e8π16\frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{8e}{64} - \frac{4\pi}{64} = \frac{e}{8} - \frac{\pi}{16}

Answer for Part c: e8π16\frac{e}{8} - \frac{\pi}{16}


Final Answers:

a) 2πe2\pi e
b) π32-\frac{\pi}{32}
c) e8π16\frac{e}{8} - \frac{\pi}{16}


Do you need any further clarifications or explanations? Let me know!

Here are 5 related questions for practice:

  1. Differentiate h(x)=f(x)g(x)h(x) = f(x) \cdot g(x) at x=2x = 2.
  2. Find the derivative of f(g(h(x)))f(g(h(x))) using the chain rule.
  3. Evaluate ddx[xf(x)]\frac{d}{dx} \left[ x \cdot f(x) \right] at x=2x = 2.
  4. Differentiate 1g(x)\frac{1}{g(x)} at x=2x = 2.
  5. Find ddx[g(x)2]\frac{d}{dx} \left[ g(x)^2 \right] at x=2x = 2.

Tip: Always identify the derivative rule (chain, product, or quotient) before solving.

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Math Problem Analysis

Mathematical Concepts

Chain Rule
Quotient Rule
Derivative of Reciprocal Functions
Differentiation

Formulas

Chain Rule: \( \frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x) \)
Reciprocal Rule: \( \frac{d}{dx} \left[ \frac{1}{f(x)} \right] = -\frac{f'(x)}{(f(x))^2} \)
Quotient Rule: \( \frac{d}{dx} \left[ \frac{g(x)}{f(x)} \right] = \frac{g'(x)f(x) - g(x)f'(x)}{(f(x))^2} \)

Theorems

Chain Rule
Quotient Rule
Derivative Rules

Suitable Grade Level

Undergraduate Calculus or Advanced High School Calculus