Multiplying and Dividing Functions

Multiplying and Dividing Functions

Multiplying and dividing functions is similary to multiplying and dividing polynomials. Learn how to multiply and divide functions in this post. 

Step by step guide to Multiplying and Dividing Functions

  • Just like we can multiply and divide numbers, we can multiply and divide functions. For example, if we had functions \(f\) and \(g\), we could create two new functions: \(f × g\), and \(\frac{f}{g}\).

Example 1:

\(g(x)=x+1, f(x)=x-2\), Find: \((g.f)(2)\)

Answer:

\((g.f)(x)=g(x).f(x)=(x+1)(x-2)=x^2-2x+x-2=x^2-x-2 \)
Substitute \(x\) with \(2\):
\((g.f)(x)=x^2-x-2=(2)^2-2-2=4-2-2=0 \)

Example 2:

\(f(x)=x-2, h(x)=x+8\), Find: \((\frac{f}{h})(-1)\)

Answer:

\((\frac{f}{h})(x)=\frac{f(x)}{h(x)} =\frac{x-2}{x+8} \)
Substitute x with \(-1: (\frac{f}{h})(x)=\frac{x-2}{x+8}=\frac{(-1)-2}{(-1)+8}=\frac{-3}{7}=-\frac{3}{7} \)

Example 3:

\(g(x)=-x-2, f(x)=2x+1\), Find: \((g.f)\)

Answer:

\((g.f)(x)=g(x).f(x)=(-x-2)(2x+1)=-2x^2-x-4x-2=-2x^2-5x-2 \)

Example 4:

\(f(x)=x+4, h(x)=5x-2\), Find: \((\frac{f}{h})\)

Answer:

\((\frac{f}{h})(x)=\frac{f(x)}{h(x)} =\frac{x+4}{5x-2} \)

Exercises

Perform the indicated operation.

  • \(\color{blue}{g(a) = 2a – 1 \\ h(a) = 3a – 3 \\ Find \ (g.h)(– 4) } \\\ \)
  • \(\color{blue}{f(x) = 2x^3 – 5x^2 \\ g(x) = 2x – 1 \\ Find \ (f.g)(x)} \\\ \)
  • \(\color{blue}{g(t) = t^2 + 3 \\ h(t) = 4t – 3 \\ Find \ (g.h)(– 1)} \\\ \)
  • \(\color{blue}{g(n) = n^2 + 4 + 2n \\ h(n) = – 3n + 2 \\ Find \ (g.h)(1)} \\\ \)
  • \(\color{blue}{g(a) = 3a + 2 \\ f(a) = 2a – 4 \\ Find (\frac{g}{f})(3) } \\\ \)
  • \(\color{blue}{f(x) = 3x – 1 \\ g(x) = x^2 – x \\ Find \ (\frac{f}{g})(x)}\)

Download Multiplying and Dividing Functions Worksheet

Answers

  • \(\color{blue}{135}\)
  • \(\color{blue}{4x^4 – 12x^3 + 5x^2}\)
  • \(\color{blue}{-28}\)
  • \(\color{blue}{-7}\)
  • \(\color{blue}{\frac{11}{2}} \\\ \)
  • \(\color{blue}{\frac{3x-1}{x^2-x}}\)

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