Two lenses: find Di through second lens

[tensor0910]

Homework Statement

A 1.60 cm tall object is 20.0 cm to the left of a lens with a focal length of 10.0 cm . A second lens with a focal length of 36.0 cm is 44.0 cm to the right of the first lens.

Homework Equations

1/f = 1/d_i + 1/d_o , h_i/h_o = d_i/d_o

The Attempt at a Solution

[/B]
calculate distance of image

1/f = 1/d_i + 1/d_o
1/10cm - 1/20cm = 1/d_i

20cm = d_i

with a image twice the length of the object, it must be a converging lens. its inverted and real.
image of first lens becomes object of second lens.

d_o = 20 +44 = 64cm

f = 36cm

1/36 - 1/64 = 1/d_i

82.28cm = d_i

But MP says its wrong...?

The only thing I can think of is that the signs are wrong somewhere, but the image is real so it should be positive... Any and all help is appreciated!

 

[Cutter Ketch]

image of first lens becomes object of second lens.

d_o = 20 +44 = 64cm

!

Your first image is a real image to the right of the first lens so how far is it from the second lens?

 

[tensor0910]

Your first image is a real image to the right of the first lens so how far is it from the second lens?

yup that makes sense. Thanks for the help Cutter!

 

[Cutter Ketch]

yup that makes sense. Thanks for the help Cutter!

You're welcome