it seems odd that this...
if not the you can easily draw one to find out.
its really difficult to explain how to do this in words though...
if you get a chance ask for some help on this because it can be really difficult to understand without seeing it.
i involve drawing two or three lines a different angles through the lens and using the focus to find out
but im pretty sure diverging lens the image is virtual so has to be in the positive bit....
sorry i can't be more help.

x