Answer
The image point of an unsymmetrical lens does not change if you turn the lens around.
Work Step by Step
As explained on page 670, the lensmaker’s equation is symmetrical with respect to $R_{1}$ and $R_{2}$. Flipping the lens around means a swap of $R_{1}$ and $R_{2}$, which leaves the focal length unchanged, meaning the image does not move.