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Why do you learn square roots?
Square roots are used to find the side length of a square
when you know the area of the square.
Square Root of a Number
• If b2 = a, then b is a square root of a.
Example: 32 = 9 and (-3)2 = 9, so 3 and -3
are square roots of 9.
• All positive real numbers have two square
roots, a positive square root (also called
principal square root) and a negative square
root.
Perfect Squares
• The square of an integer is called a perfect square.
– Example: 42 = 16, therefore 16 is a perfect square.
• A perfect square is a number whose positive square
root is a whole number.
– Example:
16 = 4
Perfect Squares
1
64
4
81
9
16
100
121
25
36
49
144
169
196
225
400
625
1=1
Perfect Squares
64
=8
4=2
81 = 9
=3
16 = 4
100
9
=5
36 = 6
49 = 7
25
= 10
121 = 11
144 = 12
169 = 13
196 = 14
225 =
15
400 =
20
900
= 30
121
100 =
= 11
4 =2
1=1
64
9
=8
=3
169
16
= 13
49 =
81 = 9
7
=4
144
= 12
196
= 14
10
225 =
15
400 =
20
900
25
=5
36 = 6
= 30