Page 101 - Algebra 1

L E S S O N Simplifying and Evaluating Variable
16
Expressions
Warm Up
1. Vocabulary The set of whole numbers and their opposites {..., -4, -3,
(6)
-2, -1, 0, 1, 2, 3, 4,...} is the set of . Simplify.
2. -ax2(dx3 - a5x) (15)
3. √ 36 + √ 81 - 42 (13)
4. [-(-5)] - |-7| (7)
5. Which value is equivalent to _9 (-_1 )? (11) 10 12
49 3 _3 _3 A -_60 B -_40 C 60 D 40
New Concepts To evaluate an expression that contains variables, substitute each variable in the expression with a given numeric value, and then find the value of the
expression.
Example
1
-a[-a( p - a)] = -3[-3(4 - 3)] = -3[-3(1)]
= -3[-3]
= 9
Substitute each variable with the given value. Subtract.
Multiply inside the brackets.
Multiply.
Evaluating Expressions with Two Variables
Evaluate each expression for the given values of the variables.
a. -a[-a(p - a)] for a = 3 and p = 4 SOLUTION
Hint
Use parentheses when substituting a number for a variable, so that the negative signs and the subtraction signs are not confused.
86 Saxon Algebra 1
b. (-x + a) - (x - a) for a = -2 and x = 7 SOLUTION
(-x + a) - (x - a)
= [-7 + (-2)] - [7 - (-2)] = [-7 + (-2)] - [7 + 2]
= (-9) - (9)
= -18
Substitute each variable with the given value. Take the opposite of -2.
Evaluate inside the brackets.
Subtract.