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Lesson 3-1
Example 1 Find a Square Root
Find 49 .
49 indicates the positive square root of 49.
Since 72 = 49, 49 = 7.
Example 2 Find the Negative Square Root
Find  144 .
 144 indicates the negative square root of 144.
Since (–12)( –12) = 144,  144 = –12.
Example 3 Use Square Roots to Solve an Equation
49
ALGEBRA Solve x 2 
.
81
49
Write the equation.
x2 
81
49
49
x2 
or 
Take the square root of each side.
81
81
7
7
7 7 49
 7  7  49
Notice that  
.
x  or 
and      
9
9
9 9 81
 9  9  81
7
7
The equation has two solutions,
and  .
9
9
Example 4 Use an Equation to Solve a Problem
ARCHITECTURE A house is built with a square base. The area of the base is
4,225 square feet. Determine the length of each side.
Words
Variables
Equation
Area is equal to
A
=
4,225
=
4,225 = s2
4,225  s 2
65 or –65 = s
the square of the length of a side.
s2
s2
Write the equation.
Take the square root of each side.
Use a calculator.
The length of a side of the base of the house is 65 feet since distance cannot be negative.