Ta có :
\(x_1+x_2+x_3+...+x_{2015}=0\)
\(\left(x_1+x_2\right)+\left(x_3+x_4\right)+...+\left(x_{2013}+x_{2014}\right)+x_{2015}=0\)
\(\Rightarrow1+1+...+1+x_{2015}=0\)(có 1007 chữ số 1)
\(\Rightarrow1007+x_{2015}=0\)
\(\Rightarrow x_{2015}=0-1007\)
\(\Rightarrow x_{2015}=-1007\)
Vậy x2015 = -1007