Page 156 - Algebra 1

A decimal equation can also be solved by using inverse operations without multiplying by a power of 10 first.
Example
2
Solving Two-Step Decimal Equations
Solve.
a. 0.2m + 0.8 = 1.8 SOLUTION
0.2m + 0.8 = 1.8
-__0._8 = -__0._8 0.2m = 1
0.2m = 1 __
0.2 0.2 m = 5
Subtraction Property of Equality Simplify.
Division Property of Equality
Simplify.
Math Reasoning
Verify Are 0.2m + 0.8 = 1.8 and 2m + 8 = 18 equivalent equations? Explain.
b. -0.03n - 1.2 = -1.44
SOLUTION
-0.03n - 1.2 = -1.44 +_ _ 1 . _ 2 = +_ _ 1 . _ 2
Addition Property of Equality Simplify.
Division Property of Equality
-0.03n = -0.24 -0.03n = -0.24
__ -0.03 -0.03
Math Language
_1 of100=_1 ×100=50 22
0.5 of 100 = 0.5 × 100 = 50
50%of100=0.5 ×100 = 50
“Of”means to multiply.
n=8
Finding a decimal part of a number is the same as finding a fraction or
percent of a number.
Finding Decimal Parts of Numbers
0.48 of 86 is what number?
SOLUTION
decimal number of given number is what number 0.48 · 86 = n
0.48 · 86 = n Multiply. 41.28 = n
Estimate the answer to see if it is reasonable.
0.48 is less than 0.50 or _1 . 2
_1 o f 8 6 i s 4 3 . 2
41.28 is close to 43, so the answer is reasonable.
Simplify.
Example
3
Lesson 24 141