Find all numbers for which the rational expression is underfined.
x^2+7/x^2-3x-18
This is undefined when x^2 - 3x -18 = 0
So factoring, we have
( x - 6) ( x + 3) = 0 and setting both factors to 0, x = 6 and x = -3
And these are the two values that make the rational function undefined
