The focal length of a diverging lens is negative.
f = -12 cm; u = 15 cm.
f=uvu+v
−12=15v15+v
−12(15+v)=15vimplies−180−12v=15v
−180=15v+12vimplies−180=27v
v=−18027=−6.67cm
The image is virtual and 6.67 cm from the lens.
