1-n+m=1-(n-m)=-2
(1)A+B=x^2-4x-2-2x^2+3x-1
=-x^2-x-3
(2)2A-3B=2(x^2-4x-2)-3(-2x^2+3x-1)
=2x^2-8x-4+6x^2-9x+3
=8x^2-17x-1