Question

Chứng tỏ rằng: B=1/2²+1/3²+1/4²+....+1/8²<1

Answer 1

B=1/2²+1/3²+1/4²+...+1/8² < 1/1.2+1/2.3+1/3.4+...+1/7.8=1-1/2+1/2-1/3+1/3-1/4+...+1/7-1/8

=1-1/8<1

=> B<1/1.2+1/2.3+1/3.4+...+1/7.8<1

Vậy B<1

 

Answer 2

\(B=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{8^2}