Given P(x)=xn+an−1xn−1+⋯+a0P(x) = x^n + a_{n-1}x^{n-1} + \cdots + a_0P(x)=xn+an−1xn−1+⋯+a0, if P(i)=0P(i) = 0P(i)=0 where i2=−1i^2 = -1i2=−1, what is a factor of P(x)P(x)P(x)?
x+ix+ix+i
x2−1x^2-1x2−1
x2+1x^2+1x2+1
x−1x-1x−1