1. Pre-Algebra
3-8
Squares and Square Roots
Warm Up
Simplify. 25 64
144
225
5. 202
400

2. Learn to find square roots & cube roots.
Squares and Square Roots
Learn to find square roots & cube roots.

3. 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

4. A. 49 B. 100 C. 225 Find the two square roots of each number. 49 = 7 –
49 = 7
49 = –7 –
B. 100
100 = 10
100 = –10 –
C. 225
225 = 15
225 = –15 –

5. A. 25 B. 144 C. 289 Find the two square roots of each number. 25 = 5 –
25 = 5
25 = –5 –
B. 144
144 = 12
144 = –12 –
C. 289
289 = 17
289 = –17 –

6. Watch brainpop

7. 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.

8. A square window has an area of 169 square inches
A square window has an area of 169 square inches. How wide is the window?
Find the square root of 169 to find the width of the window. Use the positive square root; a negative length has no meaning.
132 = 169
So = 13.
The window is 13 inches wide.

9. Evaluate the expression.
= 3(6) + 7 =
= 25
B –
21 – =
= 4 + 9
= 13

10. Evaluate the expression.
= 2(5) + 4 =
= 10
B –
41 – =
= 6 + 5
= 11

11. Cube roots Cube root – a factor that multiplies by itself three times
Examples

12. ±9 ±50 13 7 Lesson Quiz Find the two square roots of each number.
Evaluate each expression.
– 2 49 ±9
±50 13 7