Homework help or pointers anyone?

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The discussion revolves around calculating the height of a final image formed by a system of lenses, specifically a converging lens followed by a diverging lens. The user initially seeks help with the problem but later realizes a mistake related to sign conventions in optics. It is emphasized that drawing a diagram can aid in understanding the image formation process. The importance of correctly applying sign conventions for lens equations is highlighted as crucial for accurate results. Overall, the conversation underscores the value of careful diagramming and attention to detail in optics problems.
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homework help or pointers anyone?

A 1.29-cm-tall object is placed 31.1 cm to the left of a converging lens with a focal length f1 = 20.4 cm. A diverging lens, with a focal length f2 = -42.4 cm, is placed 31.1 cm to the right of the first lens. How tall is the final image of the object?


im not quite artistic enough to draw this picture for you sorry but any help or direction ect is appreciated
 
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got it

never mind! sorry i was stupid and missed a sign...had a positive in a number i should have had a negative
 
Sign conventionas are always a problem in optics, it is useful to always draw a rough diagram and have a feel for where the image should be for an object in front and behind the focal poitn for a concave and convex lens.
 

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