Math Problem Statement

let f(x) = (x-8)^2 find a domain in which f is one to one and non decreasing. then find the inverse of f restricted to this domain

Solution

The given function is f(x)=(x8)2f(x) = (x - 8)^2.

Step 1: Identify when f(x)f(x) is one-to-one and non-decreasing.

To ensure that a function is one-to-one and non-decreasing, its derivative must be non-negative (f(x)0f'(x) \geq 0).

Derivative of f(x)f(x):

f(x)=2(x8)f'(x) = 2(x - 8) The derivative f(x)=2(x8)f'(x) = 2(x - 8) is non-negative when x8x \geq 8.

Thus, f(x)f(x) is non-decreasing for x8x \geq 8. We will restrict the domain to x8x \geq 8 to make f(x)f(x) one-to-one and non-decreasing.

Step 2: Restrict the domain of f(x)f(x).

The domain of f(x)f(x) where it is one-to-one and non-decreasing is [8,)[8, \infty).

Step 3: Find the inverse of f(x)f(x) on this restricted domain.

To find the inverse of f(x)f(x), follow these steps:

  1. Start with y=(x8)2y = (x - 8)^2.

  2. Solve for xx in terms of yy: y=x8\sqrt{y} = x - 8 x=y+8x = \sqrt{y} + 8

    Since we are considering the domain x8x \geq 8, we only take the positive square root.

Final Answer:

  • Domain: [8,)[8, \infty)
  • Inverse function: f1(x)=x+8f^{-1}(x) = \sqrt{x} + 8, for x0x \geq 0.

Would you like further details or have any questions?

Here are some related questions to explore:

  1. What does it mean for a function to be one-to-one?
  2. How does restricting a domain affect the invertibility of a function?
  3. Why did we choose the positive square root when finding the inverse?
  4. What are the conditions for a function to have an inverse?
  5. How would the inverse change if the function had a different form?

Tip: When solving for an inverse, always check if the original function needs domain restrictions to ensure it is one-to-one.

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Derivatives
Inverse Functions

Formulas

Derivative of a function: f'(x)
Inverse of a function: If y = f(x), then x = f^(-1)(y)

Theorems

The derivative test for monotonicity
Conditions for a function to have an inverse

Suitable Grade Level

Grades 10-12