Question

tính hợp lí nếu có thể

\(a.\frac{-5}{9}+\frac{5}{9}:\left(1\frac{2}{3}-1\frac{1}{12}\right)\)

\(b.\frac{7}{25}.\frac{11}{13}-\frac{7}{25}.\frac{2}{13}-\frac{18}{25}\)

\(c.\frac{18}{11.13}+\frac{18}{13.15}+........+\frac{18}{99.101}\)

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Answer 1

khó quá 

Answer 2

\(a.\frac{-5}{9}+\frac{5}{9}:A=\left(-\frac{5}{9}+\frac{5}{9}\right):A=0:A=0\)

\(b.\frac{7}{25}.\frac{11}{13}-\frac{7}{25}.\frac{2}{13}-\frac{8}{25}=\frac{7}{25}.\left(\frac{11}{13}-\frac{2}{13}\right)-\frac{8}{25}=\frac{7}{25}.\frac{9}{13}-\frac{8}{25}=\frac{63}{325}-\frac{8}{25}=\frac{-41}{325}\)

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Answer 3

ad biy sai câu b

Answer 4

c) = \(\frac{18}{11}-\frac{18}{13}+\frac{18}{13}-\frac{18}{15}\) +...+\(\frac{18}{99}-\frac{18}{100}\) 

=\(\frac{18}{11}+\frac{18}{100}\) 

=\(\frac{1998}{1100}\)