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? (4 points)

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? (4 points)

ankit042 · Answer

@pmiddleton6 you know how to factor x^2-x-2?

anonymous · Answer

no please help

ankit042 · Answer

you can write x^2-x -2 as x^2 -2x +x -2
x(x-2)+1(x-2)=0
(x-2)(x+1)=0
x=2 or x=-1

ankit042 · Answer

For the part B you can easily check the factors by putting value of x in the equation if result is zero then factors are correct!

anonymous · Answer

okay thank you very much

ankit042 · Answer

dHope you got the concept

anonymous · Answer

Could you explain part two a little bit more?

ankit042 · Answer

np so f(x) = x^2 -x-2
for the values of x which are factors of the quadratic equation value of f(x) will be =0
so you can directly check by putting value of x

ankit042 · Answer

In this example John got x as 1 and -2 ; so if we calculate f(1) we get 1-1-2 f(1)=-2 and f(-2)=4
so we knpw he made a mistake

anonymous · Answer

oh okay i get it!!

ankit042 · Answer

Great!