Question

a concave mirror produces three times enlarged image of an object at place 10cm in front of it calculate the radius of curvature of the mirror

Answer 1

Hope this helps :)
Done it using the lens formula, and the formula for magnification.

Answer 2

magnification in mirror is given by m = -v/u

where v = position of image , u = position of object

m =-3 , u = -10 cm

m = -v/(-10)

-3*(-10) = -v

v= - 30

we know , R = 2uv/ (u+v)

R = 2(-10)(-30)/(-40)

R = -15

radius of curvature = -15 cm

Hope it helps....