2X-y-3=0 求8-4x+2y

问题描述:

2X-y-3=0 求8-4x+2y

2x-y=3
8-4x+2y=8-2(2x-y)=8-2*3=2

2X-y-3=0
2x-y=3
8-4x+2y =8-(4x-2y)=8-2*(2x-y)=8-2*3=2

8-4x+2y
= -(4x-2y-8)
= -2(2x-y-3 -1)
= -2(0-1)
=2