The expression that should be added to the polynomial f(x) = x4 + 2x3 – 2x2 + x + 1, so that it should be exactly divisible by (x2 + 2x – 3) is
What must be subtracted from polynomial f(x)=x4+2x3−13x2−12x+21 so that the resulting polynomial is exactly divisible by x2−4x+3 ?