# How do you demonstrate that, if #(df)/(dr)= (dg)/(dy)#, then #(df)/(dr)= (dg)/(dy) = K # where K is a constant ?

##### 1 Answer

EDIT : I'm sorry i allow myself to edit your answer and answer my own question

#### Explanation:

explanation here :

Let's say that if

the only way the equality is respected is that the functions are equal to the same constant.

EDIT 2:

For the math

we derivate both side by