xy+ 2=0,x+y-3=0求(3xy+10y))+[5x-(2xy+2y-3x)]

xy+ 2=0,x+y-3=0求(3xy+10y))+[5x-(2xy+2y-3x)]
xy+ 2=0,x+y-3=0求(3xy+10y))+[5x-(2xy+2y-3x)]

xy+ 2=0,x+y-3=0求(3xy+10y))+[5x-(2xy+2y-3x)]
即xy=-2
x+y=3
原式=3xy+10y+5x-2xy-2y+3x
=xy+8x+8y
=xy+8(x+y)
=-2+8×3
=22

∵xy+2=0，x+y-3=0
∴xy=-2，x+y=3
(3xy+10y)+[5x-(2xy+2y-3x)]
=3xy+10y+(5x-2xy-2y+3x)
=3xy+10y+5x-2xy-2y+3x
=xy+8x+8y
=xy+8(x+y)
=(-2)+8×3
=-2+24
=22

解(3xy+10y))+[5x-(2xy+2y-3x)]
=(3xy+10y))+（5x-2xy-2y+3x)
=3xy+10y+（8x-2xy-2y）
=3xy+10y+8x-2xy-2y
=xy+8y+8x
=xy+8（x+y）
=-2+8×3
=22