若xy=-2,x+y=3,求代数式(3xy+10y)+5x- (2xy+2y-3x)的值

问题描述:

若xy=-2,x+y=3,求代数式(3xy+10y)+5x- (2xy+2y-3x)的值

先化简为3xy+10y+5x-2xy-2y+3x=xy+8(x+y)=-2+8*3=22
很详细了啊!

(3xy+10y)+5x- (2xy+2y-3x)
=3xy+10y+5x-2xy-2y+3x
=8x+xy+8y
=8(x+y)+xy
=8*3+(-2)
=24-2
=22

(3xy+10y)+5x- (2xy+2y-3x)
=3xy+10y+5x-2xy-2y+3x
=xy+8x+8y
=-2+8(x+y)
=-2+24
=22