2
1
1
1
10
10
v −
= −
or
v2 = ¥
The virtual image is formed at an infinite distance to the left of the
second lens This acts as an object for the third lens 3
3
3
1
1
1
v
u
f
−
=
or
  
3
1
1
1
30
v =
+
∞
or
v3 = 30 cm
The final image is formed 30 cm to the right of the third lens 9