Math Problem Statement

Find (f^{-1})'(-3) if f(x) = x^3 - 3x.

Solution

The problem is asking to find (f1)(3)(f^{-1})'(-3) given that f(x)=x33xf(x) = x^3 - 3x.

To solve this, let's follow these steps:

  1. Understand the Problem: To find (f1)(3)(f^{-1})'(-3), we can use the formula: (f1)(y)=1f(x)(f^{-1})'(y) = \frac{1}{f'(x)} where y=f(x)y = f(x). Here, we need f(x)=3f(x) = -3 to find the corresponding xx and then use f(x)f'(x) for that xx value.

  2. Find xx such that f(x)=3f(x) = -3: Given f(x)=x33xf(x) = x^3 - 3x, we need to solve: x33x=3x^3 - 3x = -3 Rearrange this to: x33x+3=0x^3 - 3x + 3 = 0 Solving this equation for xx will give us the values needed.

  3. Differentiate f(x)f(x): The derivative of f(x)=x33xf(x) = x^3 - 3x is: f(x)=3x23f'(x) = 3x^2 - 3

  4. Evaluate f(x)f'(x) at the appropriate xx value: Once we find the correct xx that satisfies f(x)=3f(x) = -3, we can substitute it into f(x)f'(x) to find (f1)(3)(f^{-1})'(-3).

Let me know if you'd like a step-by-step solution for solving for xx and finishing the calculations.

Here are related questions to expand your understanding:

  1. How do we find the inverse of a function algebraically?
  2. Why does the formula (f1)(y)=1f(x)(f^{-1})'(y) = \frac{1}{f'(x)} work for derivatives of inverse functions?
  3. What techniques can be used to solve cubic equations like x33x+3=0x^3 - 3x + 3 = 0?
  4. How do we know if a function has an inverse over its entire domain?
  5. What is the significance of differentiability in finding inverses?

Tip: When working with derivatives of inverse functions, ensure that f(x)f(x) is one-to-one in the region you're analyzing, as this guarantees an inverse exists for that range.

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Math Problem Analysis

Mathematical Concepts

Calculus
Inverse Function Derivative
Differentiation

Formulas

(f^{-1})'(y) = 1 / f'(x) where y = f(x)

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 11-12