3xy-[2xy-2(xy-2分之3xy)+xy]+3xy,其中x=3,y=负3分之一大神们帮帮忙

问题描述:

3xy-[2xy-2(xy-2分之3xy)+xy]+3xy,其中x=3,y=负3分之一大神们帮帮忙

=3xy-2xy+2(xy-3xy/2)-xy+3xy =3xy-2xy+2xy-3xy-xy+3xy =xy+xy =xy(y+1) =3x(-1/3)(-1/3+1) =-2/3 满意请及时采纳!谢谢!