A spherical mirror forms an image of magnification 3. The object distance, if focal length of mirror is 24 cm, may be

m=ff−u3=−24−24−u or    −24−u=−8 or u+24=8 or   u=(8−24)cm=−16cm  If m=−3, then −3=−24−24−uu+24=−8 or  u=−32cm Note that the magnification is greater than 1, so mirror cannot be convex.