If ( + k) is a factor of fx), which of the following must be true? f(k) =0
f-k) =0
A root of fx) is x=k.
Ayintercept of fX) is x=-k.

based on context clues you gave i'm assuming the answer would be c.

explanation:

previous steps have made pa≅ pb ≅ st ≅ su. setting the compass width to ab allows you to make tu the same length. then δstu ≅ δpab by the sss congruence postulate, and ∠p ≅ ∠s by the reason cpctc.