Math Problem Statement

What is the INVERSE of f(x) = 2(x - 4)^2 +6

Solution

To find the inverse of the function f(x)=2(x4)2+6f(x) = 2(x - 4)^2 + 6, follow these steps:

Step 1: Replace f(x)f(x) with yy

y=2(x4)2+6y = 2(x - 4)^2 + 6

Step 2: Swap xx and yy

To find the inverse, we switch xx and yy: x=2(y4)2+6x = 2(y - 4)^2 + 6

Step 3: Solve for yy

Subtract 6 from both sides:

x6=2(y4)2x - 6 = 2(y - 4)^2

Divide by 2:

x62=(y4)2\frac{x - 6}{2} = (y - 4)^2

Take the square root of both sides:

y4=±x62y - 4 = \pm \sqrt{\frac{x - 6}{2}}

Add 4 to both sides:

y=4±x62y = 4 \pm \sqrt{\frac{x - 6}{2}}

Step 4: Select the positive or negative branch

Since f(x)=2(x4)2+6f(x) = 2(x - 4)^2 + 6 is a parabola that opens upwards, it’s a one-to-one function on the restricted domain where x4x \geq 4. Therefore, we select the positive square root to keep the function and its inverse consistent:

y=4+x62y = 4 + \sqrt{\frac{x - 6}{2}}

Step 5: Final answer for the inverse

f1(x)=4+x62f^{-1}(x) = 4 + \sqrt{\frac{x - 6}{2}}


Would you like further details on this process or any specific clarifications?

Here are 5 questions to expand on this topic:

  1. What are the domain and range of f(x)f(x) and its inverse?
  2. How would the inverse change if the parabola opened downwards?
  3. How can you verify that the inverse is correct?
  4. Why is the inverse a square root function?
  5. How would the process change if the function had a different transformation?

Tip: To verify an inverse function, check that f(f1(x))=xf(f^{-1}(x)) = x and f1(f(x))=xf^{-1}(f(x)) = x.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Inverse Functions
Quadratic Functions
Square Root Functions

Formulas

Inverse function process: switch x and y, solve for y
Quadratic function: f(x) = a(x-h)^2 + k
Square root: y = ±√x

Theorems

One-to-One Function Theorem
Inverse Function Theorem

Suitable Grade Level

Grades 10-12