Question

Tính giá trị biểu thức:

      \(A=\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+...+\frac{5}{91.93}+\frac{5}{93.95}\)

Answer 1

\(\frac{2}{5}A=\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{93.95}\)

\(\frac{2}{5}A=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{93}-\frac{1}{95}\)

\(\frac{2}{5}A=1-\frac{1}{95}=\frac{94}{95}\)

\(A=\frac{47}{19}\)

Answer 2

A= 5/1.3 +5/3.5 +5/5.7+....+5/91.93 + 5/93.95

A= 5/2 . (1-1/3+1/3-1/5+1/5-1/7+...+1/91-1/93+1/93-1/95)

A=5/2. (1-1/95)

A= 5/2 . 94/95

A=47/19

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