化简求值:2(x+y)(x-2y)-2x(x+y),其中x、y满足x^2+y^2-2x+4y=-5

问题描述:

化简求值:2(x+y)(x-2y)-2x(x+y),其中x、y满足x^2+y^2-2x+4y=-5

x、y满足x^2+y^2-2x+4y=-5
则(x-1)²+(y+2)²=0
即x=1,y=2
2(x+y)(x-2y)-2x(x+y)
=2(x+y)(x-2y-x)
=-4y(x+y)
=-8*(3)
=-24