设√x(√x-√y)=√xy+3y,求2x+3√xy-y/3x-y的值.
问题描述：
设√x(√x-√y)=√xy+3y,求2x+3√xy-y/3x-y的值.
答
√x(√x-√y)=√xy+3y
则x-√xy=√xy+3y
则x-2√xy-3y=0
(√x+√y)(√x-3√y)=0
所以√x-3√y=0
所以)√x=3√y
所以x=9y
2x+3√xy-y/3x-y=(18y+9y-y)/(27y-y)=26y/26y=1