Math Problem Statement

The functions y = f(x) = bx^2 and y = g(x) = a^x are given. Determine the values of a and b, write down a possible restriction for f(x) so that its inverse will be a function, and determine the equation of the inverse function of f.

Solution

Let's analyze the question in the image you provided.

The functions given are:

  • f(x)=bx2f(x) = bx^2
  • g(x)=axg(x) = a^x

From the graph, we need to determine values for aa and bb, as well as solve additional parts.

1.1 Determine the values of aa and bb.

f(x)=bx2f(x) = bx^2

From the graph, for the parabola f(x)f(x), it passes through the point (2,8)(-2, -8). Substituting this into the equation of f(x)f(x): f(2)=b(2)2=8f(-2) = b(-2)^2 = -8 4b=8b=24b = -8 \quad \Rightarrow \quad b = -2 Thus, f(x)=2x2f(x) = -2x^2.

g(x)=axg(x) = a^x

For the exponential function g(x)=axg(x) = a^x, it passes through the point (2,9)(2, 9). Substituting into the equation of g(x)g(x): g(2)=a2=9g(2) = a^2 = 9 a2=9a=3a^2 = 9 \quad \Rightarrow \quad a = 3 Thus, g(x)=3xg(x) = 3^x.

1.2 Write a possible restriction for f(x)f(x) so that the inverse of f(x)f(x) will be a function.

Since f(x)=2x2f(x) = -2x^2 is a parabola, to ensure its inverse is a function, we need to restrict f(x)f(x) to either the left or right half of the parabola. For example, we can restrict x0x \geq 0 or x0x \leq 0. A possible restriction would be: x0x \geq 0 This ensures that f(x)f(x) is one-to-one and its inverse will be a function.

1.3 Determine the equation of the inverse function of f(x)f(x).

To find the inverse of f(x)=2x2f(x) = -2x^2 (with the restriction x0x \geq 0):

  1. Start with y=2x2y = -2x^2
  2. Solve for xx in terms of yy: y=2x2x2=y2x=y2y = -2x^2 \quad \Rightarrow \quad x^2 = \frac{-y}{2} \quad \Rightarrow \quad x = \sqrt{\frac{-y}{2}} Since x0x \geq 0, the inverse function is: f1(x)=x2f^{-1}(x) = \sqrt{\frac{-x}{2}}

Let me know if you'd like further details or have any specific questions! Here are five related questions you can explore:

  1. What if we restrict f(x)f(x) to x0x \leq 0? What would the inverse function be?
  2. How does the domain restriction affect the range of the inverse function?
  3. Can you graph the inverse function of f(x)f(x)?
  4. What are the properties of inverse functions for quadratic equations in general?
  5. How would changing the value of bb in f(x)f(x) affect its graph and inverse?

Tip: Always remember that for a function to have an inverse, it must be one-to-one, which can often require domain restrictions for functions like quadratics.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Exponential Functions
Inverse Functions
Domain Restrictions

Formulas

f(x) = bx^2
g(x) = a^x
Inverse of quadratic functions
Inverse function formula

Theorems

One-to-One Function Theorem
Inverse Function Theorem

Suitable Grade Level

Grades 10-12