(-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1_数学解答

(-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1

人气：446 ℃　时间：2020-03-19 18:04:33

解答

(-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)
=-2xy+2x+5y-3xy-2y+2x-x-4y-xy
=-2xy-3xy-xy+2x+2x-x+5y-2y-4y
=-6xy+3x-3y
=-6xy+3(x-y)
=-6*(-1)+3*4
=6+12
=18