If F is the focal length of a convex lens and an object is placed at a distance x from the lens then its image will be at a distance y from the lens, where F,x, and y are related by the lens equation

1/F = 1/x + 1/y

Suppose that a lens has a focal length of 4.8 cm, and that the image of an object is 4cm closer to the lens than the object itself. How far from the lens is the object?

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