Download Lesson 21

Bell Quiz
Objectives
• Solve one-step equations by multiplying or
dividing.
Review: Inverse Operations
• To find the solution of an equation, isolate
the variable by using inverse operations.
• You must use the same inverse operation
on each side of the equation.
Inverse Operations
Addition <------------> Subtraction
Multiplication <------------> Division
Multiplication and Division Properties of Equality
Multiplication Property of Equality
Both sides of an equation can be multiplied by the same number,
and the statement will still be true.
Examples:
2=2
3∙2=2∙3
6=6
a=b
a∙c=b∙c
ac = bc
Division Property of Equality
Both sides of an equation can be divided by the same number, and
the statement will still be true.
Examples:
10 = 10
10 ÷ 2 = 10 ÷ 2
5=5
a=b
a ÷ c = b ÷ c (c ≠ 0)
Example 1
Solving Equations by Multiplying
Solve. Then check the solution.
x
= 8
6
Example 2
Solving Equations by Multiplying
Solve. Then check the solution.
w
–11 =
4
Lesson Practice
Solve. Then check the solution.
k
= 3
9
Lesson Practice
Solve. Then check the solution.
m
–20 =
5
Example 3
Solving Equations by Dividing
Solve. Then check the solution.
5x = 20
Example 4
Solving Equations by Dividing
Solve. Then check the solution.
–12 = 3n
Lesson Practice
Solve. Then check the solution.
8y = 24
Lesson Practice
Solve. Then check the solution.
–15 = 3x
Example 5
Solving Equations by Dividing
Solve. Then check the solution.
2
p= 7
5
Lesson Practice
Solve. Then check the solution.
3
y = 11
4
Lesson Practice
Solve. Then check the solution.
5
n
8 = –
12
Example 6
Application: Architecture
Anita is an architect. She is designing a
rectangular room that has an area of 126
square feet. If the length of the room is 12
feet, what is its width?
Lesson Practice
A rectangular pool has an area of 140
feet. If the length of the pool is 16 feet,
what is its width?