Đáp án:
\(\left\{\begin{matrix} \dfrac{1}{2^2}<\dfrac{1}{1.2} & \\ \dfrac{1}{3^2}<\dfrac 1{2.3} & \\ ....& \\ \dfrac 1{50^2}<\dfrac 1{49.50} & \end{matrix}\right.\)
\(\to\dfrac 1{2^2}+\dfrac 1{3^2}+\cdots +\dfrac{1}{50^2}<\dfrac 1{1\cdot 2}+\dfrac 1{2\cdot 3}+\cdots +\dfrac 1{49\cdot 50}=1-\dfrac 12+\dfrac 12-\dfrac 13+\cdots+\dfrac 1{49}-\dfrac 1{50}=1-\dfrac 1{50}<1\)
\(\to dpcm\)
