Answer:
Step-by-step explanation:
We have four equations here. Let's actually solve them, using factoring if possible and some other method if factoring is not possible.
A) x^2 + 5x + 4 factors into (x + 1)(x + 4), but x^2 + 5x - 4 does not.
B) x^2 + 6x + 9 factors into (x + 3)^2.
C) x^2 + 3x - 4 factors into (x + 4)(x - 1).
D) x^2 - x - 6 factors into (x - 3)(x + 2)
x^2 + 5x - 4 = 0 can be solved, but not by factoring.
