2. When u > 2f, if the image is inverted and reduced, then f > v > 2f.
When u = 2f, if it is a real image with inverted size, then v = 2f.
When f < u < 2f, if the image is inverted and enlarged, then v < 2f.
When u=f, imaging is not performed.
When u < f, the image becomes an upright and enlarged virtual image.
3、 1/u+ 1/v= 1/f
With the intensification of market competition and the acceleration of the process of world economic integration, the marketing environment in 2 1 century has undergo