Math Problem Statement

Find the inverse of the function y = 2x2 + 2.

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Solution

To find the inverse of the function y=2x2+2y = 2x^2 + 2, follow these steps:

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

The given function is y=2x2+2y = 2x^2 + 2. So, the function can be written as: f(x)=2x2+2f(x) = 2x^2 + 2

Step 2: Interchange xx and yy

To find the inverse, interchange xx and yy in the equation: x=2y2+2x = 2y^2 + 2

Step 3: Solve for yy

Now, solve this equation for yy:

  1. Subtract 2 from both sides: x2=2y2x - 2 = 2y^2

  2. Divide by 2: x22=y2\frac{x - 2}{2} = y^2

  3. Take the square root of both sides: y=±x22y = \pm \sqrt{\frac{x - 2}{2}}

Step 4: Specify the domain for the inverse

Since the original function is a parabola (which isn't one-to-one), the inverse will have two branches corresponding to y=x22y = \sqrt{\frac{x - 2}{2}} and y=x22y = -\sqrt{\frac{x - 2}{2}}.

To ensure a proper inverse, we typically restrict the domain of the original function to make it one-to-one. For example, we could restrict x0x \geq 0, meaning we only take the positive square root for the inverse.

Thus, the inverse function is: f1(x)=x22f^{-1}(x) = \sqrt{\frac{x - 2}{2}} if x0x \geq 0.

Would you like more details or have any questions?

Related Questions:

  1. How do you find the domain and range of an inverse function?
  2. What is the effect of restricting the domain on the inverse function?
  3. Can every quadratic function have an inverse? Why or why not?
  4. How do you verify that a function and its inverse are correct?
  5. What is the graph of f1(x)f^{-1}(x) for the given function?

Tip:

Always check if the original function is one-to-one before finding the inverse. If not, you may need to restrict the domain.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Quadratic Functions
Algebra

Formulas

Inverse function: f^{-1}(x)
Quadratic function: f(x) = ax^2 + bx + c

Theorems

One-to-One Function Theorem
Quadratic Function Domain Restriction

Suitable Grade Level

Grades 10-12