Math Problem Statement

Consider the functions f(x) = -2x + 3 and g(x) = -1/2(x - 3). (a) Find f(g(x)). (b) Find g(f(x)). (c) Determine whether the functions f and g are inverses of each other.

Solution

Let’s solve the given problems step by step:

(a) Find f(g(x))f(g(x))

We need to substitute g(x)=12(x3)g(x) = -\frac{1}{2}(x - 3) into f(x)=2x+3f(x) = -2x + 3.

  1. Substitute g(x)g(x) into f(x)f(x): f(g(x))=f(12(x3))f(g(x)) = f\left(-\frac{1}{2}(x - 3)\right)

  2. Replace xx in f(x)=2x+3f(x) = -2x + 3 with 12(x3)-\frac{1}{2}(x - 3): f(g(x))=2(12(x3))+3f(g(x)) = -2\left(-\frac{1}{2}(x - 3)\right) + 3

  3. Simplify: f(g(x))=(2)(12(x3))+3f(g(x)) = (-2) \cdot \left(-\frac{1}{2}(x - 3)\right) + 3 f(g(x))=(1)(x3)+3f(g(x)) = (1)(x - 3) + 3 f(g(x))=x3+3f(g(x)) = x - 3 + 3 f(g(x))=xf(g(x)) = x

Thus, f(g(x))=xf(g(x)) = x.


(b) Find g(f(x))g(f(x))

Now, substitute f(x)=2x+3f(x) = -2x + 3 into g(x)=12(x3)g(x) = -\frac{1}{2}(x - 3).

  1. Substitute f(x)f(x) into g(x)g(x): g(f(x))=g(2x+3)g(f(x)) = g\left(-2x + 3\right)

  2. Replace xx in g(x)=12(x3)g(x) = -\frac{1}{2}(x - 3) with 2x+3-2x + 3: g(f(x))=12((2x+3)3)g(f(x)) = -\frac{1}{2}\left((-2x + 3) - 3\right)

  3. Simplify: g(f(x))=12(2x+33)g(f(x)) = -\frac{1}{2}\left(-2x + 3 - 3\right) g(f(x))=12(2x)g(f(x)) = -\frac{1}{2}(-2x) g(f(x))=xg(f(x)) = x

Thus, g(f(x))=xg(f(x)) = x.


(c) Determine whether ff and gg are inverses

To determine if ff and gg are inverses of each other, both f(g(x))f(g(x)) and g(f(x))g(f(x)) must simplify to xx. From parts (a) and (b), we found:

  • f(g(x))=xf(g(x)) = x
  • g(f(x))=xg(f(x)) = x

Since both conditions are satisfied, ff and gg are inverses of each other.


Final Answers:

(a) f(g(x))=xf(g(x)) = x
(b) g(f(x))=xg(f(x)) = x
(c) ff and gg are inverses of each other.

Would you like further details on any part of this process? Here are some related questions to explore further:

  1. How do we verify if two functions are inverses graphically?
  2. Can you explain why inverse functions reflect across the line y=xy = x?
  3. What is the domain and range of f(x)f(x) and g(x)g(x)?
  4. How would ff and gg behave if they were not inverses of each other?
  5. How do we compute the inverse of a function algebraically?

Tip: Always check f(g(x))f(g(x)) and g(f(x))g(f(x)) when verifying if functions are inverses—it ensures accuracy!

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Math Problem Analysis

Mathematical Concepts

Function Composition
Inverse Functions
Algebra

Formulas

f(g(x)) = f(-1/2(x - 3))
g(f(x)) = g(-2x + 3)

Theorems

Inverse Function Theorem

Suitable Grade Level

Grades 10-12