Question
Find out the points on the curve 
at which the tangents are (i) parallel to the x-axis and (ii) parallel to the y-axis.
Solution
The equation of curve is 
Differentiating both sides w.r.t.x, we get,
(i) For the points on the curve, where tangents are parallel to x-axis.
Putting x = 0 in (1), we get,
there is no real point at which the tangent is parallel to x-axis.
(ii) For the points on the curve, where tangents are parallel to y-axis.
Putting y = 0 in (1), we get,
