Simplify each expression. Refer to the Math Notes box in this lesson for help.

1. $\sqrt { 50 }$ 

   Hint (a):

   What square number is a factor of $50$?

   More Help (a):

   Here is a list of square numbers to get you started:

   $1^2=1\\2^2=4\\3^2=9\\4^2=16\\5^2=25\\6^2=36$

2. $\sqrt { 72 }$ 

   Hint (b):

   Refer to part (a).

   More Help (b):

   To simplify completely you need to find the largest square number that is a factor of $72$.

3. $\sqrt { 45 }$ 

   Hint (c):

   Refer to part (a).