Evaluate an algebraic example

You evaluate an algebraic expression when you try to find the value of the algebraic expression by substituting a given number for each variable. 

Then you can simplify the resulting numerical expression using the order of operations.

Examples showing how to evaluate an algebraic expression.

Example #1

Evaluate 2a - 2⁵ ÷ b for a = 6 and b = 8 

Substitute 6 for a and 8 for b

2a - 2⁵ ÷ b = 2 x 6 - 2⁵ ÷ 8

Simplify the power

2a - 2⁵ ÷ b = 2 x 6 - 32 ÷ 8

Multiply and divide from left to right

2a - 2⁵ ÷ b = 12 - 4

Subtract

2a - 2⁵ ÷ b = 8

Example #2

Evaluate a² - 2b + c for a = 4, b = 6 and c = 3 

Substitute 4 for a, 6 for b, and 3 for c

a² - 2b + c = 4² - 2 x 6 + 3

Simplify the power

a² - 2b + c = 16 - 2 x 6 + 3

Perform the multiplication

a² - 2b + c = 16 - 12 + 3

Add and subtract from left to right

a² - 2b + c = 4 + 3

a² - 2b + c = 7