Question

A student performed the following steps to find the solution to the equation x^2-2x-8=0. Where did the student go wrong?

Step 1. Factor the polynomial into (x-4) and (x-2)
Step 2. x-4=0 and x-2=0
Step 3. x=4 and x=3

A. The student did not make any mistakes, the solution is correct
B. in step 1
C. in step 2
D. in step 3

Answer 1

In step 1, because you want to find factors that multiply to -8 and add to -2. So the correct factorization is (x-4)(x+2). The student got the minus sign wrong.

(Then in step 3 the x=3 is also very wrong, but that looks more like a typo).
(Also, it should be x-4=0 OR x+2=0, there is no x for which both factors are 0 at the same time!)