8. Factor.

When we multiply the first and last coefficients, (1)(-20) = -20 so we are looking for a pair of factors of 20 which have a difference of 1. There is such a pair, 4 and 5. This gives us the coefficients of the O and I terms when we recover the FOIL step.

F O I L

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

This will come form