Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter P - Section P.7 - Equations - Exercise Set - Page 106: 42


$f_{2}= \displaystyle \frac{ff_{1}}{f_{1}-f}, \quad $focal length of glasses

Work Step by Step

$f=\displaystyle \frac{f_{1}f_{2}}{f_{1}+f_{2}}$ ... multiply with the LCD, $(f_{1}+f_{2})$ $f(f_{1}+f_{2})=f_{1}f_{2}$ $ff_{1}+ff_{2}=f_{1}f_{2}$ ... transfer $f_{1}f_{2}$ to the LHS: add $-f_{1}f_{2}-ff_{1}$ $ ff_{2}-f_{1}f_{2}=-ff_{1}\quad$ ... factor out $f_{2}$ $ f_{2}(f-f_{1})=-ff_{1}\quad$ ... divide with $(f-f_{1})$ $f_{2}=\displaystyle \frac{-ff_{1}}{f-f_{1}}$ $f_{2}= \displaystyle \frac{ff_{1}}{f_{1}-f}$ (see example 5) focal length of glasses, $f_{1}=$ distance from the lens $f_{2}=$ distance from the lens to your retina
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.