I need to know what the x intercept(s) of the function

Answer:
i think it is (x-5) (x-1) (x+1) (x+3)
Step-by-step explanation:
f(x)=x 4 −2x 3 −16x 2 +2x+15=±15,±5,±3,±1=x=1=x 3 −x 2 −17x−15=0=
x 2 −2x−15=0=x= 2 2±8=x=−3 x=5= (x-5) (x-1) (x+1) (x+3)