1. Simplifying a Variable Expression
EXAMPLE 4
Simplifying a Variable Expression =
14x
7xy
2 7 x
7 x y
Factor numerator and denominator. 1
2 7 x
7 x y =
Divide out common factor. = 2 y
Simplify.

2. Evaluating a Variable Expression
EXAMPLE 5
Evaluating a Variable Expression
Evaluate the expression when x = 5.
–4x3 2x
–4x3 2x =
– x x x
2 x
Factor numerator and denominator. 1
– x x x
2 x =
Divide out common factor. =
–2x2
Simplify. =
–2(5)2
Substitute 5 for x. =
–50
Evaluate powers and simplify.

3. GUIDED PRACTICE
for Examples 4 and 5
Simplify the variable expression. Then evaluate for x = – 2 and y = 3.
12.
4xy 6x = 2y 3 = 2

4. GUIDED PRACTICE
for Examples 4 and 5
Simplify the variable expression. Then evaluate for x = – 2 and y = 3.
13.
32y
8xy = 4 y = 4 3

5. GUIDED PRACTICE
for Examples 4 and 5
Simplify the variable expression. Then evaluate for x = – 2 and y = 3.
14.
3x3y 6x =
x2y 3 = 4

6. GUIDED PRACTICE
for Examples 4 and 5
Simplify the variable expression. Then evaluate for x = – 2 and y = 3.
15.
5x2y
10xy = x 2 = –1