\(S=1+\left(\frac{1}{2}+\frac{1}{3}\right)+\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+\frac{1}{7}\right)+\left(\frac{1}{8}+...+\frac{1}{15}\right)+...+\left(\frac{1}{2^{99}}+...+\frac{1}{2^{100}-1}\right)\)
\(S=1+\left(\frac{1}{2}+\frac{1}{3}\right)+\left(\frac{1}{2^2}+\frac{1}{5}+\frac{1}{6}+\frac{1}{7}\right)+\left(\frac{1}{2^3}+...+\frac{1}{15}\right)+...+\left(\frac{1}{2^{99}}+...+\frac{1}{2^{100}-1}\right)\)
ta chia S thành 10 nhóm: 1 và 99 nhóm như trên
nhận xét:
\(\frac{1}{2}+\frac{1}{3}