Question

  A= 2^2/3x5 +2^2/5x7 +........+ 2^2/99x101

Answer 1

Ta có: \(A=\frac{2^2}{3\times5}+\frac{2^2}{5\times7}+...+\frac{2^2}{99\times101}\)

\(\Rightarrow A=2.\)< \(\frac{2}{3\times5}+\frac{2}{5\times7}+...+\frac{2}{99\times101}\)>

\(\Rightarrow A=2.< \frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{99}-\frac{1}{101}>\)

\(\Rightarrow A=2.< \frac{1}{3}-\frac{1}{101}>\)

\(\Rightarrow A=2.\frac{98}{303}\)

\(\Rightarrow A=\frac{196}{303}\)

Nhớ k nhá.