Question 436687
You can definitely factor the numerator as the other tutor did. In cases where the numerator does not factor (i.e. the general case) you would use L'Hopital's rule:


{{{lim(x->3, (x^2 + 2x - 15)/(x-3)) = lim(x->3, (2x + 2)/1) = 8}}} (take d/dx of top and bottom, evaluate the limit).