已知x+y=4,xy=3,求4{xy+2y}+{6x-[2xy-y-3x}}的值
问题描述:
已知x+y=4,xy=3,求4{xy+2y}+{6x-[2xy-y-3x}}的值
x+y=-4
答
原式=4xy+8y+6x-2xy+y+3x
=2xy+9x+9y
=2xy+9(x+y)
=6+36
=42