己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,A-B的值

问题描述:

己知A=6x+4y-5 B=2(x+y)+(x-3) (1)当x=y=-2吋,
A-B的值

A-B=(6x+4y-5)-(2(x+y)+(x-3))
=6x+4y-5-2x-2y-x+3
=3x+2y-2
=3×(-2)+2×(-2)-2
=(3+2+1)×(-2)
=6×(-2)
=-12