Question

if an object is placed BEHIND a convex mirror, with light coming from the front, is the Distance of the object and the focal length negative?

Answer 1

Object distance and focal length are on same side of mirror.

So, both of them will be negative or both will be positive depending on what sign convention you take.

If you are taking distance to the left side of mirror i.e side from which light is coming as positive, then both focal length and object distance will be negative and vice versa.