Câu hỏi 16
Tính giá trị
$$\frac1{1+11^{-2011}}+\frac1{1+11^{-2009}}+\frac1{1+11^{-2007}}+\cdots+\frac1{1+11^{2009}}+\frac1{1+11^{2011}}.$$
$$\frac1{1+11^{-2011}}+\frac1{1+11^{-2009}}+\frac1{1+11^{-2007}}+\cdots+\frac1{1+11^{2009}}+\frac1{1+11^{2011}}.$$