9514 1404 393
Answer:
see attached
Explanation:
This is made slightly more difficult by the fact that the given polynomials are not in order of decreasing powers of x. So, you need to be careful what you're adding, to make sure the terms are "like".
__
Add: (-2x² +3x +4) +(x² -4x -5) = (-2+1)x² +(3-4)x +(4-5) = -x² -x -1
Opp: -(3x² -x +1) = 3x² +x -1
Sub: (x² +3x -4) -(-2x² +4x -3) = (1-(-2))x² +(3-4)x +(-4-(-3)) = 3x² -x -1