若1/x+1/y=3,求2x-4xy+2y/-5xy+2xy-5y的值
问题描述:
若1/x+1/y=3,求2x-4xy+2y/-5xy+2xy-5y的值
十分钟内能ok吗
答
1/x+1/y=3
(2x-4xy+2y)/(-5x+2xy-5y)
=(2/y-4+2/x)/(-5/y+2-5/x)
=(6-4)/(2-15)
=-2/13