Question

when image and object distance and size is in minus or plus and when focal length is in minus or plus plz give me and fast

Answer 1

hlo anamika!!!

it's Khushi here.....

you asked that :-

when the image distance (v) and object distance (u) is in minus ....

HERE is your answer:-

object distance will always in minus , mirror doesn't matters and sign on image distance is depend upon mirror , if it is concave it will in minus & if is convex , it will in positive sign...

for more understanding u should read The concept of sign convention...
it refers to the attachment....

hope this helps!!!!