Solving a Virtual Image Problem Involving a Converging Lens

[lpau001]

Homework Statement

A converging lens of focal length 0.246 m forms a virtual image of an object. The image appears to be .933 m from the lens on the same side as the object. What is the distance between the object and the lens?

Homework Equations

1/f = 1/d_i + 1/d_o

Since the image is virtual, it would be a negative distance right?

so 1/f = -1/d_i + 1/d_o

The Attempt at a Solution

I get d_o = (.246)(.993)/(.246+.993) = .197157 m
which is wrong..

 

[Suk-Sci]

The formula1/f=1/d_i - 1/d_o