posted by shannon .
use synthetic division to show that x=2i is a zero of p(x)
Your function, which I will assume was to be
p(x) = 5x^3 - 4x^2 + 20x - 16 , factors very nicely by grouping
p(x) = 5x^3 - 4x^2 + 20x - 16
= x^2(5x-4) + 4(5x-4)
= (5x-4)(x^2 + 4)
so the zeros are
x = 4/5 and x = ± 2i
Using synthetic division for this expression is totally out of place.
lim x¨‡ 2x 3 +5x 2 −x 3 =