What is the nature of the image formed when the object is placed?

1. Virtual, erect and smaller than object
2. Real, inverted and enlarged than object
3. Real, inverted and smaller than object.
4. Virtual, erect and larger than object

Object distance (u) = - 20 m                           ( negative, due to sign convention)Focal length (f) = -10 m                                   ( negative, due to sign convention)Image distance = ?

From the mirror formula, we know that: 

`1/v+1/u=1/f` 

or `1/v+1/-20=(-1)/10` 

or `1/v-_20^1=_10^-1` 

or `1/v=(-1)/10+1/20` 

or `1/v=-1/20orv=-20m` 

Here, the negative sign means that the image is formed on the left side of the mirror. Thus, it is a real and inverted image, formed at a distance of 20 m from the mirror.