Converging lens

i does not equal 2.96. You've just dropped a variable, you can't do that. If M = -i/o, then i = -M*o, right? Remember there should be a negative sign in the magnification equation when you are dealing with object and image distances. Now you know what i is in terms of o, so using the lens equation and a little algebra you can solve for o.

 

You are still forgetting the negative sign in the M equation. To find "o", you can just take it out so you will have (1/o)*(1-(1/2.96)) on the right side of the lens equation. You can then cross multiply to solve for "o".

Once you get your answer for "o", find "i". You can put them both back into the lens equation and check if they are right, since you were given f.

 

No, you're not quite finished yet. You should be at (1/15.5) = (1/o)*(0.663). Now you must isolate "o" and solve for it. You can just cross multiply, since what you have is the same as (1/15.5)=(0.663/o). Do you see what I mean?

 

Yes, I think that looks OK.