Explanation:
It is given that,
Focal length
f=−20cm
hi=3ho
The image is three times the size of the object. So there are two cases.
Case 1. For real image
m=−uv=−3
v=3u
Using mirror’s formula
f1=v1+u1
−201=3u1+u1
u=3−80cm
Case 2. For virtual image
m=u−v=+3
v=−3u
Again using mirror’s formula
−201=−3u1+u1
u=3−40cm
The possible values of u are 3−80cmand3−40cm.
