Page 259 - Basic College Mathematics with Early Integers

236 C HAPTE R 3 I FRACTIONS

Next, combine the fractions.The LCD of 25 and 1 is 25.
16 16 25 25
- 1 = - Write 1 as .
25 25 25 25
-9 9
= or - Subtract.
25 25
Work Practice 5

1 2 11 1
PRACTICE 6 Example 6 Simplify: a + ba + b
4 3 12 4
1 1 7 1
Simplify: a- + ba + b Solution: First perform operations inside parentheses.Then multiply.
2 5 8 8
#
#
#
1 2 11 1 1 3 2 4 11 1 3
a + ba + b = a + ba + b Each LCD is 12.
#
#
#
4 3 12 4 4 3 3 4 12 4 3
3 8 11 3
= a + ba + b
12 12 12 12
11 14
= a ba b Add.
12 12
1
# #
11 2 7
= Multiply.
# #
2 6 12
1
If you find it dif- 77
ficult replacing a variable = 72 Simplify.
with a number, try the follow-
ing. First, replace the variable Work Practice 6
with a set of parentheses, then
place the replacement num-
ber between the parentheses.
4 2 Concept Check What should be done first to simplify the expression
If x = , find 2x + x . 2
5 1 5 2 4
#
2
2x + x = 2( ) + ( ) 2 5 2 - a 3 + 5 b ?
4 4 2
= 2a b + a b Á
5 5
Objective Evaluating Algebraic Expressions
then continue simplifying.
1 1
PRACTICE 7 Example 7 Evaluate 2x + y 2 if x =- and y = .
2 3
3 3
Evaluate - - xy if x = Solution: Replace x and y with the given values and simplify.
5 10
2
and y = . 1 1 2 1 1
2
3 2x + y = 2a - b + a b Replace x with - and y with .
2 3 2 3
1 1 1 2 1
= 2a- b + Write a b as .
2 9 3 9
1
=-1 + Multiply.
9
9 1
Answers
=- + The LCD is 9.
3 4 9 9 Copyright 2012 Pearson Education, Inc.
6. - 7. -
10 5 8
=- Add.
9
Concept Check Answer
Work Practice 7
Add inside parentheses.