M = \(\frac{Height\, of\, image}{Height\, of\, object}\)

= \(\frac{h_1}{h_0}\) = \(\frac{-u}{v}\)

Let the height of object be h then height of image h = – 3h

= \(\frac{3h}{h}\) = \(\frac{-v}{u}\) = \(\frac{v}{u}\) = 3

∴ Distance of object, u = – 10 cm

v = 3 × (10) = – 30 cm

Here – sign indicates, image is real and it is 30 cm in front of concave mirror.