At what distance from a biconvex lens with an optical power of 2.5 diopters should the object be placed so that its minimum

At what distance from a biconvex lens with an optical power of 2.5 diopters should the object be placed so that its minimum image is obtained at a distance of 2 m from the lens.

The optical power of a lens can be calculated using the formula:
D = 1 / d + 1 / f, where D is the optical power of the lens (D = 2.5 diopters), d is the distance from the object to the lens (m), f is the distance from the lens to the image (f = 2 m).
Let’s express and calculate the distance from the object to the lens:
d = 1 / (D – 1 / f) = 1 / (2.5 – 1/2) = 1 / (2.5 – 0.5) = 1/2 = 0.5 m.
Answer: The object must be placed at a distance of 0.5 m from the lens.