1. The problem statement, all variables and given/known data How to show that there exist no function f,g:R[itex]\nearrow[/itex]R satisfying f(x)g(y)=x+y, for all real x,y? 2. Relevant equations Any equation for showing function? 3. The attempt at a solution how about starting with sumthing like let h(x,y)=x+y ??