Pre-Algebra

3-8 Squares and Square Roots

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Pre-Algebra

3-8 Squares and Square Roots

25 64

144 225

400

1. 52 2. 82

3. 122 4. 152

5. 202

Pre-Algebra

3-8 Squares and Square Roots

Learn to find square roots & cube roots.

Squares and Square Roots

Pre-Algebra

3-8 Squares and Square Roots

Square roots• Every number has 2 square roots:

– positive square root– Negative square roots

• Principal square root is the positive square roots.

• perfect square: a number that has integers as its square roots.– Examples are 1,4,9,16, etc

Pre-Algebra

3-8 Squares and Square Roots

Find the two square roots of each number.

49 = –7–

49 = 7

100 = 10

100 = –10–

A. 49

B. 100

C. 225

225 = 15

225 = –15–

Pre-Algebra

3-8 Squares and Square Roots

A. 25

25 = –5–25 = 5

144 = 12

144 = –12–

Find the two square roots of each number.

B. 144

C. 289289 = 17

289 = –17–

Pre-Algebra

3-8 Squares and Square Roots

• Watch brainpop

Pre-Algebra

3-8 Squares and Square Roots

Joke of the day

• TEACHER: Donald, what is the chemical formula for water?

• DONALD: H I J K L M N O.• TEACHER: What are you talking about?• DONALD: Yesterday you said it's H to

O.

Pre-Algebra

3-8 Squares and Square Roots

132 = 169

The window is 13 inches wide.

Find the square root of 169 to find the width of the window. Use the positive square root; a negative length has no meaning.

A square window has an area of 169 square inches. How wide is the window?

So 169 = 13.

Pre-Algebra

3-8 Squares and Square Roots

Evaluate the expression.

A. 3 36 + 7

= 25

B. 21 – 5 + 9

= 18 + 7

= 4 + 9

= 13

3 36 + 7 = 3(6) + 7

21 – 5 + 9 = 16 + 9

Pre-Algebra

3-8 Squares and Square Roots

Evaluate the expression.

A. 2 25 + 4

= 10

B. 41 – 5 + 5

= 10 + 4

= 6 + 5= 11

2 25 + 4 = 2(5) + 4

41 – 5 + 5 = 36 + 5

Pre-Algebra

3-8 Squares and Square Roots

Cube roots

• Cube root – a factor that multiplies by itself three times

• Examples

Pre-Algebra

3-8 Squares and Square Roots

Lesson Quiz

Find the two square roots of each number.

1. 81 2. 2500

Evaluate each expression.

3. 3 16 + 1 4. 7 9 – 2 49

±9 ±50

13 7