Answer:
x^3 - x^2 + 11x - 1
-x^3 - 8x^2 + 5x + 7
Explanation:
Find the sum
(x^3+5x^2+3x-7)+(8x-6x^2+6)
=x^3+5x^2+3x-7+8x-6x^+6
Collect like terms
=x^3 +5x^2-6x^2+3x+8x-7+6
Add the like terms
= x^3 - x^2 + 11x - 1
Find the difference (7x-3x^2+2)-(x^3+5x^2+2x-5)
(7x-3x^2+2)-(x^3+5x^2+2x-5)
= 7x-3x^2+2-x^3-5x^2-2x+5
Collect like terms
= -x^3-3x^2-5x^2+7x-2x+2+5
Add the like terms
= -x^3 - 8x^2 + 5x + 7