[" A lens of power "+2" diopters is placed in contact "],[" with a lens of power - "1" diopter.The combination "],[" will behave like "]

A lens of power +3.5 diopters is placed in contact with a lens of power -2.5 diopter. The combination will behave like :

A lens of power +2 dioptres is placed in contact with a lens of power -1 dioptre. The combination will behave like

A lens of power +3.5D is placed in contact with a lens of power -2.5 D. The combination will behave like

A lens of power 6 D is put in contact with a lens of power -4 D. The combination will behave like a

a convex lens of power +6 dioptre is placed in contact with a concave lens of power -4 dioptre. What will be the nature and focal length of this combination?

a convex lens of power +6 dioptre is placed in contact with a concave lens of power -4 dioptre. What will be the nature and focal length of this combination?

A convex lens of power 4D is kept in contact with a concave lens of power 3D, the effective power of combination will be