7ху`-sqrt(xy)=7y
(7xy`)/7x=(7y/7x)+(sqrt(xy)/7x)
y`=y/x+(sqrt(xy)/7x)
dy/dx=y/x+(sqrt(xy)/7x)
dy/dx=y/x+(1/7)*sqrt(y/x) => замена y(x)/x,откуда u(x)=xy(x); dy/dx=u+x*du/dx
u+x*du/dx=y+(1/7)*sqrt(u)