I am trying to figure out if the polynomial [(x^4)+1] is reducible over Z5 and also over Z. For Z5, i tried: f(0) = 1 F(1) = 2 = f(2) = f(3) = f(4) Since neither are zero, i tried f(x) = (ax^2 + bx + c)(dx^2 + ex + f) I compared the coefficients but am unable to solve it. For Z, i have no idea how to do it. Please help! Thanks.