Evaluate expressions involving square and square roots
To evaluate an expression, you simply "plug in" the value for the variable(s)
Rewritte thi power but now with positive exponent:
if y=21 cuanto vale
Don't forget to reduce the fraction.
When an exponent is expressed as a fraction, the numerator tells you the power the number is raised to, and the denominator tells you the root you take. The order in which you perform these operations does not matter.
Rules for working with fractional exponents 
 Identify the power the number is raised to; identify the root you will find.
 Raise the number to the identified power.
 Take the identified root of the answer obtained.

Step 1 
Identify the power the number is raised to; identify the root you will find. 




Step 2 
Raise the number to the identified power 


Raise 7 to the 4th power.
74=7·7·7·7=2401


Step 3 
Take the identified root of the answer obtained. 



