SOLUTION: Find all numbers for which the rational expression is undefined. I can't remember how to do this. m^3 - 4m _________ m^2 - 64 This is supposed to look like a fraction

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Find all numbers for which the rational expression is undefined. I can't remember how to do this. m^3 - 4m _________ m^2 - 64 This is supposed to look like a fraction      Log On


   

Question 132558: Find all numbers for which the rational expression is undefined.
I can't remember how to do this.
m^3 - 4m
_________
m^2 - 64
This is supposed to look like a fraction. I can't figure out how to set it up. Sorry.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Find all numbers for which the rational expression is undefined:
%28m%5E3-4m%29%2F%28m%5E2-64%29
Ok, such an expression will be undefined whenever the denominator equals zero.
So, if you set the denominator (m%5E2-64) equal to zero then solve for the varable m, you will have your answer.
m%5E2-64+=+0 Add 64 to both sides.
m%5E2+=+64 Now take the square root of both sides.
m+=+8 or m+=+-8 These are the numbers that make the expression undefined.
Check:
%28m%5E3-4m%29%2F%28m%5E2-64%29 Substitute m = 8
%288%5E3-4%288%29%29%2F%288%5E2-64%29
%28512-32%29%2F%2864-64%29
480%2F0 Division by zero is undefined!
Similarly for m = -8
%28%28-8%29%5E3-4%28-8%29%29%2F%28%28-8%29%5E2+-+64%29
%28-512%2B32%29%2F%2864-64%29
%28-480%29%2F0 Division by zero is undefined!