John gave the following explanation for factoring the trinomial x2 – x – 2: “I need to find factors of –2. –1 and 2 multiply to –2 so my factors are (x – 1)(x + 2).”

Part 1: Are John's factors correct? If not, explain where he made his mistake.

Part 2: What could John have done to check the accuracy of his factors before submitting his Module 3 test?