This time, the product of the outer terms is 2n2 × -7 = -14n2.
The inner term is -13n.
So we are looking for 2 terms whose product is -14n2 and whose sum is -13n.
Those 2 terms are -14n and n.
(This step is nearly always easier to do with grouping method, compared to what we were doing at the top of the page.)
So we write:
2n2 − 13n − 7 |
= 2n2 − 14n + n − 7 = (2n2 − 14n) + (n − 7) = 2n(n − 7) + (1)(n − 7) = (2n + 1)(n − 7) |