Math Problem Statement

Given f(x) = 2x2 + 1 and g(x) = 7x − 9, find the following. f(g(x))

Solution

To find f(g(x))f(g(x)), we will substitute g(x)g(x) into f(x)f(x).

Given:

  • f(x)=2x2+1f(x) = 2x^2 + 1
  • g(x)=7x9g(x) = 7x - 9

Step-by-step solution:

  1. Start with f(g(x))f(g(x)). This means we substitute g(x)g(x) (which is 7x97x - 9) into f(x)f(x): f(g(x))=f(7x9)f(g(x)) = f(7x - 9)

  2. Now, substitute 7x97x - 9 into the function f(x)=2x2+1f(x) = 2x^2 + 1: f(7x9)=2(7x9)2+1f(7x - 9) = 2(7x - 9)^2 + 1

  3. Expand (7x9)2(7x - 9)^2: (7x9)2=(7x9)(7x9)=49x2126x+81(7x - 9)^2 = (7x - 9)(7x - 9) = 49x^2 - 126x + 81

  4. Now substitute this back into the function: f(7x9)=2(49x2126x+81)+1f(7x - 9) = 2(49x^2 - 126x + 81) + 1

  5. Distribute the 2: 2(49x2126x+81)=98x2252x+1622(49x^2 - 126x + 81) = 98x^2 - 252x + 162

  6. Add 1: f(g(x))=98x2252x+162+1=98x2252x+163f(g(x)) = 98x^2 - 252x + 162 + 1 = 98x^2 - 252x + 163

Thus, the final result is: f(g(x))=98x2252x+163f(g(x)) = 98x^2 - 252x + 163

Would you like any further explanation or clarification?

5 Related Questions:

  1. How do you find the inverse of a composite function like f(g(x))f(g(x))?
  2. What happens if you compute g(f(x))g(f(x)) instead of f(g(x))f(g(x))?
  3. How do you find the domain of the composite function f(g(x))f(g(x))?
  4. Can you explain how to expand and simplify binomials like (7x9)2(7x - 9)^2?
  5. How do you determine whether a composite function is one-to-one or onto?

Tip:

When composing functions, always carefully substitute the second function into the first and handle the algebra step-by-step to avoid mistakes in simplification.

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Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition
Polynomial Expansion

Formulas

f(x) = 2x^2 + 1
g(x) = 7x - 9
f(g(x)) = 2(7x - 9)^2 + 1

Theorems

Function Composition Theorem
Binomial Expansion Theorem

Suitable Grade Level

Grades 9-11