When a question asks you to "evaluate" a situation, you are most likely being asked to find a numerical answer. The process is simple. Replace the variable in the expression or equation, with the numerical value you are given, and simplify the result.

 When evaluating an expression: Remember to follow the proper order of operations and to watch out for those pesky negative signs. Placing a set of parentheses around the value being substituted will help you avoid errors with signs.

Evaluate x2 - 1, when x = 5.

Replace x with 5 and simplify.

(5)2 - 1 = 25 - 1 = 24 Answer

Evaluate a2b + a, when a = -3 and b = 2.
 Do NOT write: -32(2) + (-3) as this is -9(2) + (-3) = -21

Parentheses are needed in this problem.

(-3)2(2) + (-3) = 18 + (-3) = 15 Answer

Evaluate x3 + 3x2 - 2x - 5, when x = -4.

Again, use parentheses to avoid errors.

(-4)3 + 3(-4)2 - 2(-4) - 5 = -64 + 48 + 8 - 5 = -13 Answer

It may be the case that you will be asked to evaluate an expression using another expression.
Don't panic!!! Just follow the same process as you did when evaluating for a number.

Evaluate x2 + 2x - 4, when x = 2a.

Remember to use parentheses!

(2a)2 + 2(2a) - 4 = 4a2 + 4a - 4 Answer

Evaluate 3x + 10 when x = 3m + 15

Remember to use parentheses!

3(3m + 15) + 10 = 9m + 45 + 10 = 9m + 55 Answer

The graphing calculator can also be used to evaluate expressions.
Click on the link at the right to see the possibilities.