Question

The focal length, F, in a camera is given by the following function, where d is the distance from the lens in the camera to the object being photographed.

F = 2.24d/ d +2.24

Write an equation that expresses distance, d , as a function of the focal length, 

F .

Answer 1

Answer: D) d = -2.24F/F-2.24

Answer 2

You are asked to solve the equation given for d. As it is a proportion you can cross multiply and then isolate the d.


`F= (2.24d)/(d+2.24)`

`F(d+2.24)=2.24d`

`Fd+2.24F=2.24d`

Next factor out d to obtain


`2.24F=d(2.24-F)`

`d= (2.24F)/(2.24-F)`

Using function notation:
`G(d)= (2.24F)/(2.24-F)`