已知A=2x+4y—2,B=-2x+y+3,则3A—4B=?
问题描述:
已知A=2x+4y—2,B=-2x+y+3,则3A—4B=?
答
3A-4B
=3*(2x+4y-2)-4*(-2x+y+3)
=6x+12y-6+8x-4y-12
=(6+8)x+(12-4)y+(-6-12)
=14x+8y-18