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?

Question

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?

radar · Answer

Part 1.  To answer that you must check to see if those factors produce a -x.
When the  -x and +2x is combined, it produces a result of +x....not the desired -x. 
So do you think (x-1)(x+2) produces x^2 - x - 2 ??

radar · Answer

For part 3, John needs to verify his solution, just as we all should.