The lens formula in Cartesian coordinate system is -
where, u = object distance from optical center
v = image distance from optical center
f = focus distance from optical center
1
\(\frac{1}{f} = \frac{1}{v} - \frac{1}{u}\)
2
f = v + u
3
\(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\)
4
\(\frac{1}{f} = \frac{1}{u} - \frac{1}{v}\)