hey don't try to fool us I know your qs is wrong as whatever cas br concave never forms image between focus and pole .

real image not possible.

Explanation:

Given v = -20 cm. f = -25 cm. u = ?

Sign convention is that distances measured (from the pole of the mirror) against the direction of the rays from the object are negative.

1/f = 1/u + 1/v

1/u = 1/f - 1/v = -1/25 + 1/20 = 1//100.

But in concave mirror the object distance is negative as per the sign convention.

So the formation of real image at a distance 20 cm due to a concave mirror of focal length 25 cm isn't possible.

For a concave mirror, real image distance cannot be less than the focal length.

In a convex mirror all the images are virtual only.

Problem with the given data.