What kind of image does a concave lens form, wherever the object is placed?

1. A concave lens has a negative focal length, so the thin lens equation always returns a negative image distance. 2. A negative image distance puts the image on the same side as the object, so it cannot be projected and is virtual. 3. The magnification then comes out positive, so the image is upright. 4. Its size is always less than one, so the virtual image produced by a concave lens is always smaller than the object. 5. Only a convex lens with the object inside the focal length gives a virtual image larger than the object. _Source: OpenStax College Physics (CC BY 4.0), Ch 25 "Geometric Optics", section 25.6 Image Formation by Lenses_