# Functional Equation: f(x)+f(x+1)=(f(x+2))/(x+1)

#### Bulkyd

##### New member
Could anyone have a try with this
f(x)+f(x+1)=(f(x+2))/(x+1)

#### stapel

##### Super Moderator
Staff member
Could anyone have a try with this?

f(x)+f(x+1)=(f(x+2))/(x+1)
What were the instructions? What are you needing to do? What are your thoughts? What have you tried? How far have you gotten? Where are you stuck?

Please be complete, including class subject (real analysis? etc) and recent topics of study (such as the gamma function and the subfactorial function). Thank you! #### Bulkyd

##### New member
What were the instructions? What are you needing to do? What are your thoughts? What have you tried? How far have you gotten? Where are you stuck?

Please be complete, including class subject (real analysis? etc) and recent topics of study (such as the gamma function and the subfactorial function). Thank you! Well the instructions were to find all possible R>R functions which satisfy the above equation. I don't really know how to approach this, so help would be appreciated.

#### JeffM

##### Elite Member
Quite frankly, if those are the only instructions, I don't KNOW how to solve it. The equation is meaningless if x is minus 1 so how can it go from R, which quite obviously includes minus 1. The question does not even make sense to me.

I would probably start by trying a negative approach. What kinds of attributes must such a function NOT have. There are an infinite number of possible functions. Excluding large numbers of them strikes me as having some promise as a route to finding a solution.

#### stapel

##### Super Moderator
Staff member
Well the instructions were to find all possible R>R functions which satisfy the above equation. I don't really know how to approach this, so help would be appreciated.
What kind of class are you in? What tools and techniques have you studied recently? What did you think of the results at the link posted earlier? 