Site: TBAISD Moodle Course: Michigan Algebra I Preview 2012 Book: Adding & Subtracting Printed by: Guest user Date: Thursday, November 14, 2019, 01:51 AM

The four main operations of addition, subtraction, multiplication, and division can also be performed with functions. To add functions, combine like terms.

Example Given f(x) = 2x2 and g(x) = 3x2+ 1, what is f(x) + g(x)?

Step 1. Replace f(x) and g(x) with their equivalent expressions.

f(x) + g(x)

(2x2) + (3x2 + 1)

Step 2. Eliminate the parentheses and combine like terms.

2x2 + 3x2 + 1

5x2 + 1

Subtracting

To subtract functions, first change the sign of every term being subtracted using the Distributive Property. Eliminate the parentheses and combine like terms.

Example Given f(x) = 2x2 and g(x) = 3x2+ 1, what is f(x) - g(x)?

Step 1. Replace f(x) and g(x) with their equivalent expressions.

f(x) - g(x)

(2x2) - (3x2 + 1)

Step 2. Use the Distributive Property to change the sign of every term of g(x).

2x2 - 3x2 - 1

Step 3. Combine like terms.

-1x2 - 1 or -x2 - 1

Evaluating

Functions can also be added or subtracted given a domain value. First evaluate each function for the given domain then perform the indicated operation using the output values.

Example If f(x) = 2x2 and g(x) = 3x2 + 1, what is f(2) + g(3) ?

Step 1. Evaluate each function

f(2) = 2(2)2 = 8

g(3) = 3(3)2 + 1 = 28

Step 2. Add the output values of the two functions

f (2) + g(3)

= 8 + 28

= 36

Video Lesson

Practice