Math Problem Statement

Let f(x)=(x+1)2

Find a domain on which f is one-to-one and non-decreasing. [−1,∞)Correct

Find the inverse of f restricted to this domain f-1(x)= 

Solution

To find the inverse of f(x)=(x+1)2f(x) = (x+1)^2 restricted to the domain [1,)[-1, \infty), let's proceed step by step.

Step 1: Restate the function

The function is: f(x)=(x+1)2f(x) = (x+1)^2 and its domain is restricted to x1x \geq -1.

Step 2: Solve for xx in terms of yy

Let y=f(x)=(x+1)2y = f(x) = (x+1)^2. Solve for xx in terms of yy: y=(x+1)2y = (x+1)^2 y=x+1(take the square root on both sides)\sqrt{y} = |x+1| \quad \text{(take the square root on both sides)} Since the domain is x1x \geq -1, x+10x+1 \geq 0, so: y=x+1\sqrt{y} = x+1 x=y1x = \sqrt{y} - 1

Step 3: Write the inverse

The inverse function is: f1(x)=x1f^{-1}(x) = \sqrt{x} - 1

Step 4: Restrict the domain of the inverse

Since f(x)f(x) is defined on [1,)[-1, \infty), its range is: y=(x+1)2,x1    y0y = (x+1)^2, \quad x \geq -1 \implies y \geq 0 Thus, the domain of the inverse f1(x)f^{-1}(x) is [0,)[0, \infty).

Final Answer:

f1(x)=x1,x0f^{-1}(x) = \sqrt{x} - 1, \quad x \geq 0


Would you like additional examples or clarifications?

Here are some related questions to deepen understanding:

  1. Why is the restriction x1x \geq -1 necessary for f(x)f(x) to have an inverse?
  2. What is the graphical interpretation of f(x)f(x) and its inverse?
  3. How do we confirm f1(x)f^{-1}(x) is the correct inverse function?
  4. Can f(x)f(x) have a one-to-one inverse without restricting its domain?
  5. What happens to the inverse if the domain of f(x)f(x) is further restricted?

Tip: Always check that the domain of the original function matches the range of its inverse, and vice versa.

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Math Problem Analysis

Mathematical Concepts

Functions
Inverses of Functions
Domain and Range
Quadratic Functions

Formulas

f(x) = (x+1)^2
f^{-1}(x) = √x - 1

Theorems

Horizontal Line Test for One-to-One Functions

Suitable Grade Level

Grades 9-12