Question

The lengths of two sides of a triangle are shown below:

Answer 1

Part A

$3x^2 -2x-1+9x+2x^2 -3=\boxed{5x^2 + 7x-4}$

Part B

$(5x^3 +4x^2 - x-3)-(5x^2 + 7x-4)=\boxed{5x^3 - x^2 - 8x+1}$

Part C

No, because although they provide examples for specific polynomials being closed under addition and subtraction, there is a loss of generality.