Page 138 - Algebra 1

Write equations to solve real-world problems.
Example
3
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?
Understand
The answer will be the width of the room in feet. List the important information:
• The room is a rectangle.
• The area is 126 square feet. • The length is 12 feet.
Plan
To find the area of a rectangle, multiply the length by the width.
Solve
A = lw
126 = 12w
126 = 12w __
12 12
10_6 =w 12
Write the formula.
Substitute 126 for A and 12 for l.
Division Property of Equality Simplify.
Thewidthwillbe10_1 feet. 2
Check
Area of a rectangle = length × width 1 2 6 1 2 × 1 0 _1
2 126 = 126 ✓
Lesson Practice
Solve each equation. Then check the solution.
a. _k = 3 (Ex 1) 9
c. 8y=24 (Ex 2)
e. _3 y = 11 (Ex 2) 4
g. A rectangular pond has an area of 140 square feet. If the length of the (Ex 3) pool is 16 feet, what is its width?
b. -20 = _1 m (Ex 1) 5
d. -15=3x (Ex 2)
f. 8 = -_5 n (Ex 2) 12
Lesson 21 123