Math Problem Statement

If  f(x) = x+4  and  g(x) = 2x2-x-1, evaluate the composition (g o f)(2).

Solution

To evaluate the composition (gf)(2)(g \circ f)(2), we need to follow these steps:

  1. First, calculate f(2)f(2): f(x)=x+4f(x) = x + 4 Substituting x=2x = 2: f(2)=2+4=6f(2) = 2 + 4 = 6

  2. Now, calculate g(f(2))g(f(2)), which is g(6)g(6): g(x)=2x2x1g(x) = 2x^2 - x - 1 Substituting x=6x = 6: g(6)=2(6)261g(6) = 2(6)^2 - 6 - 1 Simplifying: g(6)=2(36)61=7261=65g(6) = 2(36) - 6 - 1 = 72 - 6 - 1 = 65

Therefore, (gf)(2)=65(g \circ f)(2) = 65.

Would you like any further details on this process or any other questions?

Related Questions:

  1. How do you evaluate compositions of functions in general?
  2. What happens if you reverse the composition, i.e., evaluate (fg)(2)(f \circ g)(2)?
  3. Can you explain how to find the domain of a composite function?
  4. How would the result change if f(x)=x2+4f(x) = x^2 + 4 instead of f(x)=x+4f(x) = x + 4?
  5. What are some applications of function compositions in real-world problems?

Tip:

When composing functions, always evaluate the inner function first, and use its result as the input for the outer function.

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Math Problem Analysis

Mathematical Concepts

Algebra
Function Composition
Quadratic Functions

Formulas

f(x) = x + 4
g(x) = 2x^2 - x - 1

Theorems

Function Composition Rule

Suitable Grade Level

Grades 9-11