When you have a rational function where factors of the numerator and denominator cancel out, you are given a hole. at the factor of x put into the new cancelled formula.
Example
f(x)=(x−7)(x+4)(x−3)(x+4)
Hole at x = -4
f(x)=x−7x−3f(−4)=−4−7−4−3=117
There is a hole at (−4,117)