\(CMR,S=\dfrac{1}{2^2}-\dfrac{1}{2^4}+\dfrac{1}{2^6}-...+\dfrac{1}{2^{4n-2}}+\dfrac{1}{2^{4n}}+...+\dfrac{1}{2^{20002}}-\dfrac{1}{2^{2004}}< 0,2\) 

\(\dfrac{\dfrac{1}{99}+\dfrac{2}{98}+\dfrac{3}{97}+...+\dfrac{99}{1}}{\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{100}}\)

Tính S=1.2.3+2.3.4+3.4.5+...+97.98.99