x2+3x-88 = 0

Since the sign of 88 is negative, think of two
integers that have product 88 and difference the
same as the coefficient of the x-term, which is 3.
Two such integers are +11 and -8.  So we factor

        (x+11)(x-8) = 0

Then we use the zero-factor property:

x+11 = 0            x-8 = 0
   x = -11            x = 5 

Edwin