Question

Please help! the answer choices are:
a)-3y
b)-3y+1
c)3y
d)3i

Answer 1

Let x be the unknown part.
y³-3y²+x-1=-i
y²(y-3)+x-1=-i
(1+i)²(1+i-3)+x-1=-i
(1+2i+i²)(i-2)+x-1=-i
recall that i²=-1, so we have 2i(i-2)+x-1=-i
2i²-4i+x-1=-i
-2-4i+x-1=-i
x=3+3i=3(1+i)=3y
so the answer is C