Ta có:[tex]M=\frac{1}{2}.\frac{3}{4}....\frac{99}{100}<\frac{2}{3}.\frac{4}{5}...\frac{100}{101}\Rightarrow M^2<\frac{1}{2}.\frac{2}{3}....\frac{99}{100}.\frac{100}{101}=\frac{1}{101}[/tex]
