1. Lesson 9.1: Radicals (Square roots)
Square Root – Inverse of squaring
“What number times itself will be the given number?”
All Numbers have TWO Square roots,
one positive and one negative.

2. Square root symbol:
- want positive answer
- want negative answer
- want both positive and negative answer
Examples: Simplify 1) 2) 3) -7 4
3, -3 or 3

3. Perfect Square – Number whose Square Root is an integer.
Ex. 1, 4, 9, 25, 81
Ex. Approximate 1) 2)
 7
 5 5 8 4 7
Can also use calculator and round answer.
Ex. 1) 3) 2) 21
-4.3
7.9

4. 3(7) 2 21 When simplifying, square root symbol is a grouping symbol.
Simplify if a = 12 and b = 4 1) 2) 3) 4
3(7) 21 2

5. Ex. Solve for the variable.1) 2)
x = 5 or -5
x = 10 or -10

6. Simplify
You can NEVER take the square root of a negative number
(pos)(pos) = pos. (neg)(neg) = pos.

7. Homework: p. 456, #16-52 evens