SOLUTION: Find all numbers for which the rational expression is undefined. r^3-8r r^2-16 (Use comma to separate answers.) I am not sure what I am doing here thank you in advance for

Algebra ->  Rational-functions -> SOLUTION: Find all numbers for which the rational expression is undefined. r^3-8r r^2-16 (Use comma to separate answers.) I am not sure what I am doing here thank you in advance for       Log On


   

Question 177689: Find all numbers for which the rational expression is undefined.
r^3-8r
r^2-16
(Use comma to separate answers.)

I am not sure what I am doing here
thank you in advance for your help
Answer by user_dude2008(1862) About Me  (Show Source):
You can put this solution on YOUR website!
Undefined when denominator is 0

r^2-16 = 0

(r+4)(r-4) = 0

r+4=0 , r-4=0

r=-4, r=4

Answer: -4, 4