Use the lens formula to show that Use the lens formula to show that f^2 = ab.

[Chikis]

Use the lens formula to show that [math]f^2 = ab[/math]. [math]f^2[/math]= square of focal length. a = object distance. b = image distance. I need help please.

The lens formular =[math]\frac{1}{f}=\frac{1}{a}+\frac{1}{b}[/math]

How do I do that?

Edited July 18, 2014 by Chikis

[rktpro]

Hint: a and b are distances measured from focus in formula 1 and from optical centre in the other.