True or false
(1±√5)/2 are zeros of the function p(x) = 4x ^4 + 8x ^3 - 7x ^2 - 21x - 9

Iwould suggest using long polynomial division in the form of p(x) / 2x - (1 +  √5) then p(x) / 2x - (1 -  √5).   if you come up with a remainder then your answer is false.   if you are not comfortable with long polynomial division you can find many videos on youtube such as khan academy.

you could keep it in the current form for synthetic division but that seems like a lot more work with that radical in the expression. 

good luck!