image distance & height of image

Question

An object 2 cm tall is placed 50 cm from a lens of 75 cm focal length. Find the image distance and the height of the image.

Answer 1

1/F = 1/d + 1/f; 1/75 = 1/50 + 1/f; f = - 150 cm.

It means that image is imajinary and strate. H/h = 150/50 = 3; H = 3h = 6 cm