Here you have the ray diagrams used to find the image position for a diverging lens. A diverging lens always form an upright virtual image.

Ray diagrams are constructed by taking the path of two distinct rays from a single point on the object:

• A ray passing through the center of the lens will be undeflected.
• A ray proceeding parallel to the principal axis will diverge as if he came from the image focal point F'.

Virtual images are produced when outgoing rays from a single point of the object diverge (never cross). The image can only be seen by looking in the optics and cannot be projected.