Page 350 - Basic College Mathematics with Early Integers

S E C T I O N 4.5 I FRACTIONS, DECIMALS, AND ORDER OF OPERATIONS 327

1
#
Example 15 The area of a triangle is Area = # base height. Find the area PRACTICE 15
of the triangle shown. 2 Find the area of the triangle.

3 feet 2.1 meters
7 meters
5.6 feet
Solution:
1
#
Area = # base height
2
1
#
= # 5.6 3
2
1
#
#
= 0.5 5.6 3 Write as the decimal 0.5.
2
= 8.4
The area of the triangle is 8.4 square feet.
Work Practice 15
Objective Using Decimals as Replacement Values

Example 16 Evaluate -2x + 5 for x = 3.8. PRACTICE 16
Evaluate 1.7y - 2 for y = 2.3.
Solution: Replace x with 3.8 in the expression -2x + 5 and simplify.

-2x + 5 =-2(3.8) + 5 Replace x with 3.8.
=-7.6 + 5 Multiply.
=-2.6 Add.
Work Practice 16

Answers
15. 7.35 sq m 16. 1.91