Division Equations

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2-8
Division Equations
Warm Up
Problem of the Day
Lesson Presentation
Course 1
2
Warm Up Solve. 1. 5x 20 2. 7n 84 3. 18 y
4 4. 21 n 3
x 4
n 12
y 22
n 18
Course 1
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Problem of the Day If 11 is 4 less than 3 times
a number, what is the number?
5
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Learn to solve whole-number division equations.
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Multiplication is the inverse of division. When
an equation contains division, use multiplication
to undo the division.
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Additional Example 1A Solving Division Equations
Solve the equation. Check your answer.
Multiply both sides by 7 to undo the division.
x 35
Substitute 35 for x in the equation.
35 is the solution.
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Additional Example 1B Solving Division Equations
Solve the equation. Check your answer.
Multiply both sides by 6 to undo the division.
78 p
Substitute 78 for p in the equation.
78 is the solution.
?
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Check It Out Example 1A
Solve the equation. Check your answer.
Multiply both sides by 2 to undo the division.
x 18
Substitute 18 for x in the equation.
18 is the solution.
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Check It Out Example 1B
Solve the equation. Check your answer.
Multiply both sides by 4 to undo the division.
288 p
Substitute 288 for p in the equation.
288 is the solution.
?
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Additional Example 2 Application
At Elk Meadows Park an aspen tree is one-third
the height of a pine tree.
height of pine
height of aspen
3
The aspen tree is 14 feet tall. How tall is the
pine tree?
Let h represent the height of the pine tree.
Multiply both sides by 3 to undo the division.
42 h
The pine tree is 42 feet tall.
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Check It Out Example 2
Jamie weighs one-half as much as her father.
fathers weight
Jamies weight
2
Jamie weighs 95 pounds. How many pounds does her
father weigh?
Let w represent her fathers weight.
Multiply both sides by 2 to undo the division.
190 w
Jamies father weighs 190 pounds.
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Lesson Quiz
Solve each equation. Check your answers.
1. 7 2. 8 3. 11 4. 7
x 70
x 32
x 99
x 105
5. The area of Sherrys flower garden is
one- fourth the area of her vegetable garden.
The area of the flower garden is 17 square feet.
Let x represent the area of her vegetable
garden. Find the area of her vegetable garden?
68 square feet