दर्पण सूत्र में, `(1)/(f)=(1)/(v)+1/u,f` u बदलने पर नहीं बदलता है।

In the mirror formula, (1)/(f)=(1)/(v)+1/u,f does not change when u is changed.

If f(x)=(u)/(v) then f'(x)=(1)/(v^(3))

The focal f to a mirror is given by (1)/(f) = (1)/(u) + (1)/(v) where u and v represent object and image distance respectively then