Math Problem Statement

If f(x) = x^2 - x + 9 and g(x) = 4x - 3, find (a) (f + g)(x) and (b) (f - g)(x), along with their domains.

Solution

Let's solve the problems shown in the image step-by-step.

Given Functions:

  1. f(x)=x2x+9f(x) = x^2 - x + 9
  2. g(x)=4x3g(x) = 4x - 3

Problem (a): Find (f+g)(x)(f + g)(x) and its domain

Solution:

(f+g)(x)=f(x)+g(x)(f + g)(x) = f(x) + g(x)

Substituting the given functions:

(f+g)(x)=(x2x+9)+(4x3)(f + g)(x) = (x^2 - x + 9) + (4x - 3)

Simplify the expression:

(f+g)(x)=x2+3x+6(f + g)(x) = x^2 + 3x + 6

Domain: Both f(x)f(x) and g(x)g(x) are polynomials, which are defined for all real numbers. Thus, the domain is:

Domain=(,)\text{Domain} = (-\infty, \infty)

Problem (b): Find (fg)(x)(f - g)(x) and its domain

Solution:

(fg)(x)=f(x)g(x)(f - g)(x) = f(x) - g(x)

Substituting the given functions:

(fg)(x)=(x2x+9)(4x3)(f - g)(x) = (x^2 - x + 9) - (4x - 3)

Simplify the expression:

(fg)(x)=x25x+12(f - g)(x) = x^2 - 5x + 12

Domain: Again, since both f(x)f(x) and g(x)g(x) are polynomials, their difference is defined for all real numbers:

Domain=(,)\text{Domain} = (-\infty, \infty)

Summary:

  1. (f+g)(x)=x2+3x+6(f + g)(x) = x^2 + 3x + 6 with Domain = (,)(- \infty, \infty)
  2. (fg)(x)=x25x+12(f - g)(x) = x^2 - 5x + 12 with Domain = (,)(- \infty, \infty)

Would you like more details on any of these steps or have any questions?

Related Questions:

  1. How do you find the sum of two functions?
  2. What are the steps to determine the domain of a function?
  3. How do you simplify algebraic expressions involving polynomials?
  4. How would the domain change if one function involved a square root?
  5. How do you verify the domain of a combined function?

Tip:

Always check the individual domains of functions before combining them, especially when dealing with fractions or square roots that could restrict the domain.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Function Operations

Formulas

(f + g)(x) = f(x) + g(x)
(f - g)(x) = f(x) - g(x)

Theorems

Polynomial functions are continuous and defined for all real numbers

Suitable Grade Level

Grades 9-12