11. Factor.

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

2*x*^{2} - 4*x* + 5*x* - 20

This comes from