1. The problem statement, all variables and given/known data With proof, Find all functions f: R->R such that f(x+y)=f(x)+f(y)+1 and f(1)=0 2. Relevant equations 3. The attempt at a solution First I cried...then... Since f(1)=0, f(2)=1, f(3)=2.....= x-1 I'm having a really hard time conceptualizing this problem and I'm not sure what the answer is suppose to look like. Is it a finite or infinite set of functions? I'm not sure. The proof part is kinda throwing me off too. Any help would be great..