Tính Nhanh
\(2\frac{3}{13}\)\(-\frac{5}{9}\)\(-\left(\frac{3}{13}+\frac{4}{9}\right)\frac{ }{ }\)
\(17\frac{4}{16}+\frac{3}{4}-\left(2\frac{3}{12}+75\%\right)\)
\(\frac{6}{5.7}+\frac{6}{7.9}+\frac{6}{9.11}+...+\frac{6}{101.103}+\frac{6}{103.106}\)
\(\frac{2}{4.7}+\frac{2}{7.10}+\frac{2}{10.13}+...+\frac{2}{25.28}\)
a) \(2\frac{3}{13}-\frac{5}{9}-\left(\frac{3}{13}+\frac{4}{9}\right)\)
= \(\frac{29}{13}-\frac{5}{9}-\left(\frac{3}{13}+\frac{4}{9}\right)\)
= \(\left(\frac{29}{13}-\frac{3}{13}\right)-\left(\frac{5}{9}+\frac{4}{9}\right)\)
= \(2-1\)
= \(1\)
b) \(17\frac{4}{16}+\frac{3}{4}-\left(2\frac{3}{12}+75\%\right)\)
= \(\frac{69}{4}+\frac{3}{4}-\left(\frac{27}{12}+\frac{3}{4}\right)\)
= \(\left(\frac{69}{4}+\frac{3}{4}\right)-\left(\frac{27}{12}+\frac{3}{4}\right)\)
= \(18-3\)
= \(15\)
c) \(\frac{6}{5.7}+\frac{6}{7.9}+\frac{6}{9.11}+....+\frac{6}{101.103}+\frac{6}{103.106}\)
= \(3.\left(\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}+....+\frac{2}{101.103}+\frac{2}{103.106}\right)\)
= \(3.\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+...+\frac{1}{101}-\frac{1}{103}+\frac{1}{103}-\frac{1}{106}\right)\)
= \(3.\left(\frac{1}{5}-\frac{1}{106}\right)\)
= \(3.\frac{101}{530}\)
= \(\frac{303}{530}\)