The correct answer is that a factor of f(x) is (x+1)
This is due to the zero product property, which states that if two binomials multiply to 0, then one of its factors must equal 0.
(x+1) must equal 0.
(x+1)=0
x=-1
If (x-1)=0, then x would equal 1 instead of -1 which is what the question is asking for.
