The curve y−exy+x=0 has a vertical tangent at the point
(1,1)
No point
(0,1)
(1,0)
dydx=−fxfy=∞=yexy−11−xexy∴1−xexy=0∴exy=1x.Alsoexy=x+y∴x+y=1x This relation is statisfied by (1,0) only.