# Hwk Problem about Convex Mirrors

#### shawonna23

An object that is 31 cm in front of a convex mirror has an image located 20 cm behind the mirror. How far behind the mirror is the image located when the object is 19 cm in front of the mirror?

For this problem, I know I have to use the mirror equation but I keep getting the wrong answer. The answer I got was -12.3 cm. What am I doing wrong? Please help!!

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#### Dr.Brain

Maybe you are not using the sign convention correctly.I advice you to imagine that the convex-mirror is placed at the origin and the distances tot he right are to be taken positive and on the left to be taken negative.Use the simple mirror-formula and try to calculate it again using correct sign-convention.

Bj

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