A linear form in k variables is an expression of the form P(x1,...,xk)=a1x1+...+akxk with real constants a1,...,ak. Prove that there exist a positive integer n and linear forms P1,...,Pn in 2017 variables such that the equation x1⋅x2⋅...⋅x2017=P1(x1,...,x2017)2017+...+Pn(x1,...,x2017)2017 holds for all real numbers x1,...,x2017.