Ta có:\(\frac{1}{1^2}+\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}\)
\(=\frac{1}{1.1}+\frac{1}{2.2}+\frac{1}{3.3}+...+\frac{1}{50.50}\)
\(=\frac{1}{1}-\frac{1}{1}+\frac{1}{2}-\frac{1}{2}+\frac{1}{3}-\frac{1}{3}+...+\frac{1}{50}-\frac{1}{50}\)
\(=0\)
Do 0<2
Nên A<2