Using graphing to check your answers is helpful. When you factor a trinomial into two binomials, each binomial represents a linear relationship. If you plot the two binomials (which are just lines) on a graph, what do they have in common with a plot of the trinomial itself? More important than that, how can this information be used to check your answer, when factoring a trinomial?
This explains the relationship between teh graphs of binomials and trinomials.