one assumption i made is the symbol is a diverging lens
http://budiprasetyoutomo.blogspot.com/2010/04/diverging-lens.html[img]http://2.bp.blogspot.com/_QpEB6X7do_8/S8UpnCYu1JI/AAAAAAAAAK0/L7ICzUFihGg/s200/image002.gif[/img]

if this assumption is valid, then
maybe u can explore this http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1155.0
and find out yourself.

picture 1 seems possible, u know where? appears to me to be at F on the right [img]http://www.phy.ntnu.edu.tw/ntnujava/index.php?action=dlattach;topic=2312.0;attach=4492;image[/img]

pictue 2 seems to require the object to be an infinity on the right side

picture 3 i cant get it, is it a trick question?