Question

[Nhi Ngọc]

Tìm a)\(A=\frac{1}{14.17}+\frac{1}{17.20}+...+\frac{1}{161.164}\)

b) \(B=\frac{2}{13.19}+\frac{2}{19.25}+...+\frac{2}{613.619}\)

Answer 1

[l҉o҉n҉g҉ d҉z҉]

\(A=\frac{1}{3}.\left(\frac{1}{14}-\frac{1}{17}+\frac{1}{17}-\frac{1}{20}+......+\frac{1}{161}-\frac{1}{164}\right)\)

\(B=\frac{1}{3}.\left(\frac{1}{13}-\frac{1}{19}+.....+\frac{1}{613}-\frac{1}{619}\right)\)

Answer 2

[ngô ân thanh tuyết]

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