Math Problem Statement

The table above gives selected values for a differentiable and decreasing function \( f \) and its derivative. If \( g(x) = f^{-1}(x) \) for all \( x \), which of the following is a correct expression for \( g'(2) \)?

Solution

To determine g(2)g'(2) for g(x)=f1(x)g(x) = f^{-1}(x), we need to use the relationship between the derivatives of inverse functions. For an inverse function g(x)=f1(x)g(x) = f^{-1}(x), the derivative is given by:

g(x)=1f(g(x))g'(x) = \frac{1}{f'(g(x))}

We are asked to find g(2)g'(2), so we need to evaluate g(2)g'(2) using this formula.

Step-by-Step Solution:

  1. Since g(x)=f1(x)g(x) = f^{-1}(x), we have g(2)=yg(2) = y where f(y)=2f(y) = 2.
  2. From the table, f(2)=5f(2) = 5, so we need to find yy such that f(y)=2f(y) = 2.
  3. Observing the table, f(2)=5f(2) = 5 and f(4)=2f(4) = 2, so g(2)=4g(2) = 4.
  4. Now, substitute g(2)=4g(2) = 4 into the derivative formula: g(2)=1f(g(2))=1f(4)g'(2) = \frac{1}{f'(g(2))} = \frac{1}{f'(4)}
  5. From the table, f(4)=5f'(4) = -5, so: g(2)=15=15g'(2) = \frac{1}{-5} = -\frac{1}{5}

Conclusion:

The correct answer is (C) g(2)=15g'(2) = -\frac{1}{5}.

Would you like more details or have any questions?

Here are five related questions:

  1. How does the derivative formula for inverse functions work in general?
  2. Why is it essential to use f(g(x))f'(g(x)) instead of f(x)f'(x) when calculating g(x)g'(x)?
  3. How can you verify the values of g(x)g(x) in such inverse function problems?
  4. What would g(0)g'(0) be for this function if needed?
  5. How does the behavior of f(x)f(x) being decreasing affect g(x)g'(x)?

Tip: When dealing with inverse functions, remember to match the input and output of each function carefully, as it’s easy to mix them up!

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Math Problem Analysis

Mathematical Concepts

Calculus
Inverse Functions
Derivatives

Formulas

g'(x) = \frac{1}{f'(g(x))}

Theorems

Derivative of Inverse Functions

Suitable Grade Level

Grades 11-12 or AP Calculus