Question

when does one go to such shop​

Answer 1

Answer:

So the image distance is positive here. you can easily verify that the focal length is in the positive x direction for a convex lens while it is along the negative x direction for a concave lens. So f is positive for a convex lens and negative for a concave lens. The reason is the sign altering of v.

Answer 2

Answer:

yesterday

good afternoon friends

have a good time