anh vẫn on à

we have four lessons today

\(f,1-\dfrac{13}{9}:\dfrac{8}{19}+-\dfrac{11}{9}:\dfrac{8}{19}\)

\(=1-\dfrac{13}{9}.\dfrac{19}{8}+\dfrac{-11}{9}.\dfrac{19}{8}\)

\(=1-\left(\dfrac{13}{9}+\dfrac{-11}{9}\right).\dfrac{19}{8}\)

=\(=1-\dfrac{2}{9}.\dfrac{19}{8}\)

\(=1-\dfrac{19}{36}\)

=\(=\dfrac{17}{36}\)

\(e,\dfrac{3}{7}.\left(\dfrac{13}{8}-\dfrac{7}{9}\right)-\dfrac{5}{8}.\left(\dfrac{3}{7}-\dfrac{8}{15}\right)\)

\(=\dfrac{3}{7}.\dfrac{13}{8}-\dfrac{3}{7}.\dfrac{7}{9}-\dfrac{5}{8}.\dfrac{3}{7}-\dfrac{5}{8}.\dfrac{8}{15}\)

\(=\dfrac{3}{7}.\left(\dfrac{13}{8}-\dfrac{5}{8}\right)-\dfrac{3}{7}.\dfrac{7}{9}-\dfrac{5}{8}.\dfrac{8}{15}\)

\(=\dfrac{3}{7}.1-\dfrac{1}{3}-\dfrac{1}{3}\)

\(=\dfrac{3}{7}-\dfrac{1}{3}+\left(-\dfrac{1}{3}\right)\)

\(=\dfrac{3}{7}-\left[\dfrac{1}{3}+\left(-\dfrac{1}{3}\right)\right]\)

\(=\dfrac{3}{7}-1\)

\(-\dfrac{4}{7}\)

nhiều quá tách ra đi bạn