Question

what polynomial could you add to 3x^4 - 9x^3 + 5x^2 - x + 7 to get a sum of 3+4x^4 + 3x-x^3 + 3x^2

Answer 1

x^4 + 8x^3 - 2x^2 - 4x - 4. I just thought of it like the second polynomial plus the polynomial you need to solve for equals the first polynomial.