Page 102 - Algebra 1

Example
2
Evaluating Expressions with Three Variables
Evaluate each expression for the given values of the variables.
a. (yx)(zyx) for x = 2, y = -1, and z = 4 SOLUTION
(yx)(zyx)
= [(-1)(2)][(4)(-1)(2)] = (-2)(-8)
= 16
Substitute each variable with the given value. Multiply inside the brackets.
Multiply.
b. _x(4ap) fora=1,p=5,andx=-3 xp
SOLUTION
_x(4ap) xp
= (-3)(4)(1)(5) __
Substitute each variable with the given value.
-15
An expression can be simplified before it is evaluated.
Simplifying Before Evaluating Expressions
Simplify each expression. Then evaluate it. Justify each step.
a. -x(y - 3) + y for x = 0.5 and y = -1.75 SOLUTION
(-3)(5) = _-60 = 4
Multiply and simplify.
Example
3
Math Reasoning
Verify Evaluate Example 3a without simplifying first to show that the answer is the same.
-x(y - 3) + y
= -xy + 3x + y
= -(0.5)(-1.75) + 3(0.5) + (-1.75) = 0.875 + 1.5 - 1.75
= 0.625
b. x(x + 2y) - x for x = _1 and y = _1
SOLUTION
x(x + 2y) - x = x2 + 2xy - x
_12 _1_1_1 = (2 ) + 2(2 )(4 )- (2 )
= _1 + _1 - _1 = 0 442
Distributive Property Substitute.
Multiply and add.
Distributive Property Substitute.
Use order of operations to simplify.
Online Connection www.SaxonMathResources.com
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Lesson 16 87