已知x-y=3则5(x-y)-3x+3y-2=
问题描述:
已知x-y=3则5(x-y)-3x+3y-2=
答
5(x-y)-3x+3y-2=
=5(x-y)-3(x-y)-2
=2(x-y)-2
=2×3-2
=4