Math Problem Statement

Four functions are given, f(x)=3x+5, g(x)=x/3 -5, h(x)= x/3 - 5/3, j(x)= 3x+15 solve f(g(x)) and g(f(x))

Solution

Let's solve for both f(g(x))f(g(x)) and g(f(x))g(f(x)) step by step.

1. Solving f(g(x))f(g(x)):

The function f(x)=3x+5f(x) = 3x + 5 and g(x)=x35g(x) = \frac{x}{3} - 5.

To find f(g(x))f(g(x)), substitute g(x)g(x) into f(x)f(x):

f(g(x))=f(x35)f(g(x)) = f\left( \frac{x}{3} - 5 \right)

Now apply the function f(x)=3x+5f(x) = 3x + 5:

f(g(x))=3(x35)+5f(g(x)) = 3\left( \frac{x}{3} - 5 \right) + 5

Distribute the 3:

f(g(x))=3×x33×5+5=x15+5f(g(x)) = 3 \times \frac{x}{3} - 3 \times 5 + 5 = x - 15 + 5

Simplify:

f(g(x))=x10f(g(x)) = x - 10

2. Solving g(f(x))g(f(x)):

Now, we want to find g(f(x))g(f(x)), where g(x)=x35g(x) = \frac{x}{3} - 5 and f(x)=3x+5f(x) = 3x + 5.

Substitute f(x)f(x) into g(x)g(x):

g(f(x))=g(3x+5)g(f(x)) = g(3x + 5)

Now apply the function g(x)=x35g(x) = \frac{x}{3} - 5:

g(f(x))=3x+535g(f(x)) = \frac{3x + 5}{3} - 5

Simplify:

g(f(x))=3x3+535=x+535g(f(x)) = \frac{3x}{3} + \frac{5}{3} - 5 = x + \frac{5}{3} - 5

Combine terms:

g(f(x))=x+53153=x103g(f(x)) = x + \frac{5}{3} - \frac{15}{3} = x - \frac{10}{3}

Final Results:

  • f(g(x))=x10f(g(x)) = x - 10
  • g(f(x))=x103g(f(x)) = x - \frac{10}{3}

Would you like more details on any step or further clarifications?

Here are 5 related questions to explore:

  1. How would the result change if f(x)f(x) were a quadratic function?
  2. Can you compute f(h(x))f(h(x)) and h(f(x))h(f(x))?
  3. What happens if you compose f(x)f(x) with itself, i.e., f(f(x))f(f(x))?
  4. What are the inverses of f(x)f(x) and g(x)g(x), and can you verify the compositions using them?
  5. How would you approach composing three functions, say f(g(h(x)))f(g(h(x)))?

Tip: Function composition can be thought of as feeding the output of one function as the input to another. Understanding the inner workings of each function helps simplify the overall expression.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition

Formulas

f(x) = 3x + 5
g(x) = x/3 - 5
f(g(x)) = f(x/3 - 5)
g(f(x)) = g(3x + 5)

Theorems

Function Composition
Linear Functions

Suitable Grade Level

Grades 9-11