[tex](1+1)^{2018}=\textrm{C}_{2018}^{0}+\textrm{C}_{2018}^{1}+...+\textrm{C}_{2018}^{2018}[/tex] (1)
[tex](1-1)^{2018}=\textrm{C}_{2018}^{0}-\textrm{C}_{2018}^{1}+...+\textrm{C}_{2018}^{2018}[/tex] (2)
Lấy (1) + (2)
=> Tổng trên bằng [tex]2^{2017}[/tex]