Download 3-6 Solving Equations Containing Decimals

3-6 Solving Equations Containing Decimals
Warm Up
Solve.
1. x – 17 = 32
2. y + 11 = 41
3. w = 18
5
4. 12x = 108
5. x – 9 = 20
3-6 Solving Equations Containing Decimals
Students in a physical education class were running
40-yard dashes as part of a fitness test. The slowest
time in the class was 3.84 seconds slower than the
fastest time of 7.2 seconds.
You can write an equation to represent this situation.
The slowest time s minus 3.84 is equal to the fastest
time of 7.2 seconds.
s – 3.84 = 7.2
3-6 Solving Equations Containing Decimals
Remember!
You can solve an equation by performing the
same operation on both sides of the equation
to isolate the variable.
3-6 Solving Equations Containing Decimals
Additional Example 1: Solving Equations by Adding
or Subtracting
Solve.
A. n – 2.75 = 8.3
B. a + 32.66 = 42
3-6 Solving Equations Containing Decimals
Check It Out: Example 1
Solve.
A. a – 1.35 = –22
B. b + 27.51 = 36
3-6 Solving Equations Containing Decimals
Additional Example 2A: Solving Equations by
Multiplying or Dividing
Solve.
x
4.8 = 5.4
3-6 Solving Equations Containing Decimals
Additional Example 2B: Solving Equations by
Multiplying and Dividing
Solve.
9 = 3.6d
3-6 Solving Equations Containing Decimals
Check It Out: Example 2A
Solve. Justify your steps.
c
9.6 =
8
3-6 Solving Equations Containing Decimals
Check It Out: Example 2B
Solve. Justify your steps.
9 = 2.5 d
3-6 Solving Equations Containing Decimals
Additional Example 3: Problem Solving Application
The fee to place a standard classified add is $29.95
for 25 words. The cost for each additional word is
$0.25. Isabel has $33.20 to place a classified ad.
How many additional words can she purchase?
1
Understand the Problem
List the important information:
• The fee to place a classified add is $29.95 for 25 words.
• The cost for each additional word is $0.25.
• Isabel has $33.20 to place an ad.
3-6 Solving Equations Containing Decimals
Additional Example 3 Continued
2
Make a Plan
Because you know how much money Isabel
has to spend, you can write an equation
with w being the number of additional words
she can purchase.
29.95 + 0.25w = 33.20
3-6 Solving Equations Containing Decimals
Additional Example 3 Continued
3
Solve
29.95 + 0.25w = 33.20
3-6 Solving Equations Containing Decimals
Additional Example 3 Continued
4
Look Back
You can round 33.20 to 33, and 29.95 to
30 to estimate how many additional words
Isabel can include.
3-6 Solving Equations Containing Decimals
Check It Out: Example 3
Hannah is driving 525 miles to visit her family.
She drove 138.1 miles before she stop to get
gas. If she averages 53 miles per hour for the
rest of her trip, how many more hours will it
take to arrive at her destination?
138.1 + 53h = 525