rational expression

[bdot]

Find all numbers for which the rational expression is not defined.

x^2-36
_________

x^2-3x-18

I think that it is either x=6 and x= -6 or x=3 and x = -6 Can anyone look at this with me... and let me know what they come up with.. thank you and walk me through if possible..

 

[wjm11]

x^2-36
_________

x^2-3x-18

The rational expression is not defined when the denominator equals zero:

x^2-3x-18 = 0
(x – 6)(x + 3) = 0
x = 6 or -3

Additional info: If this function (f(x) = (x + 6)(x - 6)/[(x – 6)(x + 3)] were graphed, there would be a vertical asymptote at x = -3 and a removable discontinuity (a hole) at x = 6.