A concave mirror has a radius of curvature of 36cm. At what distance from the mirror should an object be placed to give a real image three times the size of...

A concave mirror has a radius of curvature of 36cm. At what distance from the mirror should an object be placed to give a real image three times the size of the object?

Answer Details

F = $\frac{uv}{u+v}$

v = 3u

18 = $\frac{3u\times u}{3u+u}$

u = 24cm