11. Factor.

2x2 + x - 10

When we multiply the first and last coefficients, we get   -20.   So we need to survey all possible ways to multiply up numbers to get   20   to find a pair that has a difference of   1.

We find that   5   and   4   satisfy our conditions. This allows us to recover the FOIL step.

F     O     I     L

2x2 - 4x + 5x - 20

This comes from

(2x + 5)(x - 2)

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