Two thin lenses of power +5 D and -2 D are placed in contact with each other. Focal length of the combination is

Two thin lenses of power +5 D and -2 D are placed in

1.	Two thin lenses of power +5 D and -2 D are placed in contact with each other. Focal length of the combination is
A.	+3 m
B.	-3 m
C.	0.33 m
D.	-0.33 m
Answer» D. -0.33 m