是不是x-5√xy-6y=0?
(√x-6√y)(√x+√y)=0
x>0,y>0则√x+√y>0
所以√x-6√y=0
√x=6√y
x=36y
所以√xy=6y
所以原式=(36y-12y+y)/(36y+6y-2y)
=25y/40y
=5/8