Math Problem Statement

find the composite function ( f o g)(x) for f(x)=sqrtx+7 and g(x)=8x-11

Solution

To find the composite function (fg)(x)(f \circ g)(x), substitute g(x)g(x) into f(x)f(x). That is:

(fg)(x)=f(g(x))(f \circ g)(x) = f(g(x))

Given: f(x)=x+7andg(x)=8x11f(x) = \sqrt{x} + 7 \quad \text{and} \quad g(x) = 8x - 11

Step 1: Substitute g(x)g(x) into f(x)f(x)

Replace xx in f(x)f(x) with g(x)g(x): f(g(x))=g(x)+7f(g(x)) = \sqrt{g(x)} + 7

Substitute g(x)=8x11g(x) = 8x - 11: f(g(x))=8x11+7f(g(x)) = \sqrt{8x - 11} + 7

Final Composite Function:

(fg)(x)=8x11+7(f \circ g)(x) = \sqrt{8x - 11} + 7


Would you like a step-by-step example with a specific xx value to further explain this? Let me know! 😊

Related Questions:

  1. What is (gf)(x)(g \circ f)(x) for the same f(x)f(x) and g(x)g(x)?
  2. How do we find the domain of (fg)(x)(f \circ g)(x)?
  3. What happens if we compose these functions in the reverse order?
  4. Can (fg)(x)(f \circ g)(x) ever equal zero? Solve for xx.
  5. How do you graph (fg)(x)(f \circ g)(x) effectively?

Tip:

Always check the domain of the composite function after finding it, as the domain of g(x)g(x) and the square root in f(x)f(x) can restrict the overall domain.

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Math Problem Analysis

Mathematical Concepts

Function Composition
Square Roots
Substitution

Formulas

(f o g)(x) = f(g(x))

Theorems

Definition of Function Composition

Suitable Grade Level

Grades 9-11