# Math Help - general point of inflexion

1. ## general point of inflexion

When a general point of inflexion has a stationary point where the gradient is vertical I have noticed that the first derivative is not equal to zero at this point and neither is the second. Is this a corner case of general points of inflexion? The equation I was using is ((x+3)/4)^1/3. The point is at (-3,0).

2. ## Re: general point of inflexion

When the tangent line is vertical \displaystyle \begin{align*} \frac{dx}{dy} = 0 \end{align*}.