Hello, If you have an object, and a bi-convex lense, you are given the focal length, and you are given the magnification factor (M) to be 2, how are there two possibilities to place the object? One question I was doing asked this, and said: a) if the image is virtual, and M=2, find the distance. b) if the image is real, and M=2 find the distance. Basically, i found one answer easily, and noticed that the absolute value of the difference between my distance and the focal length, equaled the absolute value of the other distance and the focal length. So is this always the case?