由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少?_数学解答

由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少?

人气：340 ℃　时间：2019-11-10 11:07:20

解答

2(x+xy)-[(xy-3y)-x]-(-xy)
=2x+2xy-xy+3y+x+xy
=3x+3y+2xy
=3（x+y）+2xy
=3*（-2）+2*3
=0