1、若n-m=3,则2m-2n=6;1-n+m=
问题描述:
1、若n-m=3,则2m-2n=6;1-n+m=
2、设A=x^2-4x-2,B=-2x^2+3x-1,求:(1)A+B (2)2A-3B
答
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