1.已知x+4y=-1 xy=5 求（6xy+7y)+[8x-(5xy-y-6x)]的值
问题描述：
1.已知x+4y=-1 xy=5 求（6xy+7y)+[8x-(5xy-y-6x)]的值
额 那么X和Y等于多少的值应该怎么求啊。题目果然打错了
答
题目写错
应该是求（6xy+7y)+[8x-(5xy-y+6x)]
（6xy+7y)+[8x-(5xy-y+6x)]
=6xy+7y+8x-5xy+y-6x
=xy+2x+8y
=xy+2(x+4y)
=5+2×(-1)
=5-2
=3