An object O is placed in front of a small plane mirror M_1 and a large convex mirror M_2 of focal length f. The distance between O and M_1 is x and the distance between M_1 and M_2 is y. The images of O formed by M_1 and M_2 coincide. The magnitude of f is

An object O is placed in front of a small plane mirror M_1 and a large

1.	An object O is placed in front of a small plane mirror M_1 and a large convex mirror M_2 of focal length f. The distance between O and M_1 is x and the distance between M_1 and M_2 is y. The images of O formed by M_1 and M_2 coincide. The magnitude of f is
Answer» `x-y` `(x^2-y^2)/(2Y)` `(x^2+y^2)/(2y)` `(x^2+y^2)/(x+y)` ANSWER :B