若x+2y=1,2x-3y=2,则2x+4y-6/2+6x-9y/4=?

问题描述:

若x+2y=1,2x-3y=2,则2x+4y-6/2+6x-9y/4=?

x+2y=1,2x-3y=2,
则2x+4y-6/2+6x-9y/4
=2(x+2y)-6/2+3(2x-3y)/4
=2*1-6/2+3*2/4
=-2+3/2
=-1/2