Question

cho A= 6/3.5+9/5.8+12/8.12+15/12.17

Answer 1

A = 3 ​(1/3 - 1/5 + 1/5 - 1/8 + 1/8 - 1/12 + 1/12 - 1/17) = 3(1/3 - 1/17) = 14/17

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Answer 2

A = \(\frac{6}{3}.5+\frac{9}{5}.8+\frac{12}{8}.12+\frac{15}{12}.17\)

    \(=3\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{12}+\frac{1}{12}-\frac{1}{17}\right)\)

    \(=3\left(\frac{1}{3}-\frac{1}{17}\right)\)

    \(=3\times\frac{14}{51}\)

    \(=\frac{14}{17}\)

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