Question

A=1/2x2+1/2x3+1/3x4+...+1/49x50

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Answer 1

\(A=\frac{1}{2.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\)

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

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

\(\Rightarrow A=\frac{12}{25}\)

Vậy \(A=\frac{12}{25}\)