Question

13. Why can convex mirrors only produce virtual images?

Sadly, I can't find this answer in my book. :(
Any help would be appreciated, please and thank you!
stella
An virtual image is an image that is formed not by the intersection of two light beams, but it appears that these light beams intersect at some point. The optics of convex mirror doesn't allow the light beams to intersect at any position of object in relation to the mirror. Thus one can never get any real image using convex mirror