The focal length of a concave mirror when an object is placed at a distance of 15 cm and the image formed at 10 cm in front of the mirror will be?

The focal length of a concave mirror when an object is placed at a distance of

15 cm

and the image formed at

10 cm

in front of the mirror will be

6 cm

(front of the mirror).
Given,
The Focal length of the concave mirror,

v = - 10 cm

Distance of the object from the mirror,

u = - 15 cm

Now using the mirror formula;

\frac{1}{v} + \frac{1}{u} = \frac{1}{f}

\frac{1}{f} = - \frac{1}{10} + (- \frac{1}{15})

\frac{1}{f} = - \frac{1}{6}

Therefore,

f = - 6 cm

Since it’s a concave mirror, the negative sign indicates the image is formed in front of the mirror.

The focal length of a concave mirror when an object is placed at a distance of $15 cm$ and the image formed at $10 cm$ in front of the mirror will be?