Question

Please explain if its positive it Negative.
object distance in a concave mirror
image distance in a concave mirror.
focal length in a concave mirror

Answer 1

According to the sign convention

All the distance left from the pole are taken as Negative and distances to right side of pole are taken as Positive

So focal length of concave mirror is Negative

And distances above the principal axis are taken as Positive and distance below are taken as Negative

So

Image distance in a concave mirror is Negative

and object distance in a concave mirror is positive

Answer 2

In a conave mirror the object distance is +ve n image distance is taken as -ve