Question

Please answer this question asap!

Answer 1

(F1 +F2 )sum of focal length of both lenses

Answer 2

Since inversion is a symmetrical phenomenon, it follows that the rays are not affected in any other property but orientation. A light Ray coming parallel to the principle axis is converged at focus of the lens, and the converse is true too. Ensuing this, the point of intersection of rays is the focal point of lens with focal length f1, i.e. it is f1 units away from lens one.

Following the converse, since the beam is unaffected, as stated at commencement, the rays are still parallel. So, the point of intersection ought to be focal point of lens with focal length f2, hence f2 units away from it.

This makes the lens, a total of, (f1+f2) away.