Question

Please Answer Fast.......​

Answer 1

Magnification m=v/u=height of image/height of object.

v= image distance

u=object distance

m=3×height of object/height of object

Or, m=3.

v/u=3, so v=3u.

Now we know, 1/f= 1/v - 1/u

1/f= 1/3u -1/u

= -2/3u

Now, 15= -3u/2

Therefore, u= -10 units