I was trying to factor this polynomial:
$x^3 + x^2 - 16x + 20$
There are four options in this question:
- (a) It could be factored in the following form: $(x^2 + b)(x+c)$;
- (b) It could be factored in the following form: $(x+b)(x+c)(x+d)$, assuming that $b \neq c \neq d$
- (c) It could not be factored.
- (d) It could be factored in the following form: $(x+b)^2 (x+c) $
Here's how I've tried to do it: I've tried to factor by grouping the x, therefore I've obtained: $x(x^2 + x - 16) + 20$. Now, I've put the $x$ and the $20$ together: $(x+20)(x^2 + x - 16)$. Then, I've tried to factor the second term: $(x+20)(x-16)(x+1)$. So, the answer would be "b", according to this algorithm.
I've completed the test (it's a simulation for the admission test I'm going to do), I submit the answers, and I've noticed that this question isn't correct.