tính nhanh :
a) \(6\dfrac{5}{7}-\left(1\dfrac{3}{4}+2\dfrac{5}{7}\right)\)
b) \(7\dfrac{5}{11}-\left(2\dfrac{3}{7}+3\dfrac{5}{11}\right)\)
c) \(\dfrac{1}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{6}{5}-\dfrac{4}{3}\)
d) \(\left(\dfrac{-4}{5}+\dfrac{4}{3}\right)+\left(\dfrac{-5}{4}+\dfrac{14}{5}\right)-\dfrac{7}{3}\)
e) \(\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{14}+1\dfrac{5}{7}\)
a) \(6\dfrac{5}{7}-\left(1\dfrac{3}{4}+2\dfrac{5}{7}\right)\)
\(=6\dfrac{5}{7}-1\dfrac{3}{4}-2\dfrac{5}{7}\)
\(=\left(6\dfrac{5}{7}-2\dfrac{5}{7}\right)-1\dfrac{3}{4}\)
\(=4-1\dfrac{3}{4}\)
\(=3\dfrac{3}{4}\)
b) \(7\dfrac{5}{11}-\left(2\dfrac{3}{7}+3\dfrac{5}{11}\right)\)
\(=7\dfrac{5}{11}-2\dfrac{3}{7}-3\dfrac{5}{11}\)
\(=\left(7\dfrac{5}{11}-3\dfrac{5}{11}\right)-2\dfrac{3}{7}\)
\(=4-2\dfrac{3}{7}\)
\(=2\dfrac{3}{7}\)
c) \(\dfrac{1}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{6}{5}-\dfrac{4}{3}\)
\(=\dfrac{1}{3}.\left(\dfrac{4}{5}+\dfrac{6}{5}\right)+\dfrac{4}{3}\)
\(=\dfrac{1}{3}.2+\dfrac{4}{3}\)
\(=\dfrac{2}{3}+\dfrac{4}{3}\)
\(=\dfrac{6}{3}\)
\(=2\)
d) \(\left(\dfrac{-4}{5}+\dfrac{4}{3}\right)+\left(\dfrac{-5}{4}+\dfrac{14}{5}\right)-\dfrac{7}{3}\)
\(=\dfrac{-4}{5}+\dfrac{4}{3}+\dfrac{-5}{4}+\dfrac{14}{5}-\dfrac{7}{3}\)
\(=\left(\dfrac{-4}{5}+\dfrac{14}{5}\right)+\left(\dfrac{4}{3}-\dfrac{7}{3}\right)+\dfrac{-5}{4}\)
\(=\dfrac{10}{5}+\dfrac{-3}{3}+\dfrac{-5}{4}\)
\(=2+\left(-1\right)+\dfrac{-5}{4}\)
\(=1+\dfrac{-5}{4}\)
\(=\dfrac{-1}{4}\)
e) \(\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{11}+1\dfrac{5}{7}\)
\(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+1\dfrac{5}{7}\)
\(=\dfrac{-5}{7}.1+1\dfrac{5}{7}\)
\(=1+0=1\)
