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16 tháng 9 2015

=112/7.(7/13.20+7/20.27+...+7/62.69)

=16.(1/12-1/20+1/20-1/27+...+1/62-1/69)

=16.(1/13-1/69)=896/897

25 tháng 7 2019

\(\frac{112}{13.20}+\frac{112}{20.27}+\frac{112}{27.34}+...+\frac{112}{62.69}\)

\(16.\left(\frac{7}{13.20}+\frac{7}{20.27}+\frac{7}{27.34}+...+\frac{7}{62.69}\right)\)

\(16.\left(\frac{1}{13}-\frac{1}{20}+\frac{1}{20}-\frac{1}{27}+\frac{1}{27}-\frac{1}{34}+...+\frac{1}{62}-\frac{1}{69}\right)\)

\(16.\left(\frac{1}{13}-\frac{1}{69}\right)\)

\(16.\frac{56}{897}\)

\(\frac{896}{897}\)

\(\frac{112}{13.20}+\frac{112}{20.27}+\frac{112}{27.34}+...+\frac{112}{62.69}\)

\(=16\left(\frac{7}{13.20}+\frac{7}{20.27}+\frac{7}{27.34}+...+\frac{7}{62.69}\right)\)

\(=16\left(\frac{1}{13}-\frac{1}{20}+\frac{1}{20}-\frac{1}{27}+...+\frac{1}{62}-\frac{1}{69}\right)\)

\(=16\left(\frac{1}{13}-\frac{1}{69}\right)=\frac{16}{13}-\frac{16}{69}\)

16 tháng 9 2016

36346

19 tháng 8 2017

Ta có: 

  \(A=\frac{112}{13.20}+\frac{112}{20.27}+.........+\frac{112}{62.69}\)

\(\Rightarrow A=112.\left(\frac{1}{13.20}+\frac{1}{20.27}+..........+\frac{1}{62.69}\right)\)

\(\Rightarrow A=16.\left(\frac{7}{13.20}+\frac{7}{20.27}+.......+\frac{7}{62.69}\right)\)

\(\Rightarrow A=16.\left(\frac{1}{13}-\frac{1}{20}+\frac{1}{20}-\frac{1}{27}+........+\frac{1}{62}-\frac{1}{69}\right)\)

\(\Rightarrow A=16.\left(\frac{1}{13}-\frac{1}{69}\right)\)

\(\Rightarrow A=16.\frac{56}{897}\)

\(\Rightarrow A=\frac{896}{897}\)

Vậy: \(A=\frac{896}{897}\)

19 tháng 8 2017

\(A=\frac{112}{13.20}+\frac{112}{20.27}+\frac{112}{27.34}+...+\frac{112}{62.69}\)

\(\Rightarrow A=112.\left(\frac{1}{13.20}+\frac{1}{20.27}+\frac{1}{27.34}+...+\frac{1}{62.69}\right)\)

\(\Rightarrow A=112.\frac{7}{7}.\left(\frac{1}{13.20}+\frac{1}{20.27}+\frac{1}{27.34}+...+\frac{1}{62.69}\right)\)

\(\Rightarrow A=112.\frac{1}{7}\left(\frac{7}{13.20}+\frac{7}{20.27}+\frac{7}{27.34}+...+\frac{7}{62.69}\right)\)

\(\Rightarrow A=16\left(\frac{1}{13}-\frac{1}{20}+\frac{1}{20}-\frac{1}{27}+\frac{1}{27}-\frac{1}{34}+...+\frac{1}{62}-\frac{1}{69}\right)\)

\(\Rightarrow A=16\left(\frac{1}{13}-\frac{1}{69}\right)\)

\(\Rightarrow A=16.\frac{56}{897}\)

\(\Rightarrow A=\frac{896}{897}\)

\(Can\)\(you\) \(k\) \(for\) \(me,everyone?\)

\(=\left[16\cdot\left(\dfrac{1}{13}-\dfrac{1}{20}+\dfrac{1}{20}-\dfrac{1}{27}+...+\dfrac{1}{62}-\dfrac{1}{69}\right)\right]:\dfrac{-112}{897}\)

\(=16\left(\dfrac{1}{13}-\dfrac{1}{69}\right)\cdot\dfrac{-897}{112}\)

\(=-\dfrac{897}{7}\cdot\dfrac{56}{897}=-8\)