已知：|x+4y+1|+(xy-5)²=0 求代数式﹙6xy+7y﹚﹢[8x﹣﹙5xy-y+6x﹚]的值

分类: 作业答案 • 2021-12-19 22:19:45

问题描述：

答

∵：|x+4y+1|+(xy-5)²=0
∴x+4y+1=0
xy-5=0
∴x+4y=-1
xy=5
﹙6xy+7y﹚﹢[8x﹣﹙5xy-y+6x﹚]
=6xy+7y+8x-5xy+y-6x
=xy+2(x+4y)
=5-2
=3