Question

In some books there is give m=-v/u and in others there is given m=v/u which one is correct, are both correct?(PS- I know m=v/u for lens)

Answer 1

both are correct.
1st one is used for mirrors and another one for lens

Answer 2

ya it's right .........but in concave lens m=-v/u. and convex lens m=v/u ok