Remember that the product of two binomials on a single variable is a trinomial of the form:
Comparing with the coefficients of the trinomial:
We should find two numbers a and b such that a+b=12 and a*b=-13.
Since the product a*b is negative, one number should be negative and the other should be positive. Notice that 13+(-1)=12 and (13)(-1)=-13. Then those numbers are 13 and -1. Therefore:
