Question

[Thu Ngọc]

ChoA=1/1^2+1/2^2+1/3^2+1/4^2+...+1/50^2

Chung minh A <2

Answer 1

[Không cần biết]

\(A< \frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\)

\(=1-\frac{1}{50}< 1< 2\Rightarrow A< 2\Rightarrowđpcm\)

Answer 2

[Thu Ngọc]

thanks ban vi minh dang rat can dap an nay