Algebra I –Wilsen
Unit 5: Exponents
Day Two
BLOCK 2
Reference Sheet – Keep This Handy!!
Common Squares and Cubes
Roots
You can think of roots as being the opposite of exponents.
The radical sign x means: UNDO the square, and “take the square root of x”.
The square root is the number that can be squared to get x.
Example 1 : Square Roots
(a)
16 _________
What number squared equals 16?
(b)
1 _________
What number squared equals 1?
(c)
25 _________
What number squared equals 25?
A radical sign with a 3 –
3
x – means: UNDO the cube, or “take the cube root of x”.
The cube root is the number that can be cubed to get x.
Example 2 : Cube Roots
(a)
3
27 _________
What number cubed equals 27?
(b)
3
216 _________
What number cubed equals 216?
(c)
3
–8 _________
What number cubed equals –8?
A radical sign can use any number as the index.
Example 4
(a)
4
16 _________
“What is the 4th root of 16?”
What number to the 4th power equals 16? (What number, multiplied by
itself 4 times, equals 16?)
(b)
4
256 _________
“What is the 4th root of 256?”
What number to the 4th power equals 256? (What number, multiplied by
itself 4 times, equals 256?)
(c)
5
243 _________
“What is the 5th root of 243?”
What number to the 5th power equals 243? (What number, multiplied by
itself 5 times, equals 243?)
(d)
5
–32 _________
“What is the 5th root of –32?”
What number to the 5th power equals –32? (What number, multiplied by
itself 5 times, equals –32?)