X+Y=2 XY=3 求 2【XY+(-3x)】-3(2Y-XY)的值
问题描述:
X+Y=2 XY=3 求 2【XY+(-3x)】-3(2Y-XY)的值
我做了一半了,2【XY+(-3x)】-3(2Y-XY)=2XY-6X-6Y=3xy=5xy-6x-6y
答
解
2[xy+(-3x)]-3(2y-xy)
=2xy-6x-6y+3xy
=5xy-6(x+y)
=5×3-6×2
=15-12
=3X,Y的值怎么求?其余的我都会,给讲一下吧! ~(@^_^@)~不用求,5xy中xy=3-6(x+y)中x+y=2都直接代入就可以了