Bài 1:Tính:
a,\(\dfrac{-5}{13}\) . \(\dfrac{2}{11}\) + \(\dfrac{-5}{11}\) . \(\dfrac{9}{13}\) + 1 b,\(\dfrac{-8}{9}\) + \(\dfrac{1}{9}\) . \(\dfrac{2}{9}\) + \(\dfrac{1}{9}\) . \(\dfrac{7}{9}\)
c,\(\dfrac{-2}{3}\) . \(\dfrac{5}{11}\) + \(\dfrac{-2}{3}\) . \(\dfrac{2}{11}\) + \(\dfrac{-2}{3}\) . \(\dfrac{4}{11}\) d,\(\dfrac{-5}{11}\) . \(\dfrac{14}{15}\) + \(\dfrac{-5}{11}\) . \(\dfrac{12}{15}\) - \(\dfrac{-5}{11}\)
e,\(\dfrac{13}{47}\) . \(\dfrac{1}{8}\) + \(\dfrac{13}{47}\) . \(\dfrac{1}{2}\) + \(\dfrac{13}{47}\) . \(\dfrac{-13}{8}\) - \(\dfrac{34}{47}\)
a, \(\dfrac{-5}{13}.\dfrac{2}{11}+\dfrac{-5}{11}.\dfrac{9}{13}+1\)
\(=\dfrac{-10}{143}+\dfrac{-45}{143}+1\)
\(=\dfrac{-5}{13}+1\)
\(=\dfrac{8}{13}\)
b, \(\dfrac{-8}{9}+\dfrac{1}{9}.\dfrac{2}{9}+\dfrac{1}{9}.\dfrac{7}{9}\)
\(=\dfrac{-8}{9}+\dfrac{1}{9}.\left(\dfrac{2}{9}+\dfrac{7}{9}\right)\)
\(=\dfrac{-8}{9}+\dfrac{1}{9}.1\)
\(=\dfrac{-8}{9}+\dfrac{1}{9}=\dfrac{-7}{9}\)
c, \(\dfrac{-2}{3}.\dfrac{5}{11}+\dfrac{-2}{3}.\dfrac{2}{11}+\dfrac{-2}{3}.\dfrac{4}{11}\)
\(=\dfrac{-2}{3}.\left(\dfrac{5}{11}+\dfrac{2}{11}+\dfrac{4}{11}\right)\)
\(=\dfrac{-2}{3}.1=\dfrac{-2}{3}\)
d, \(\dfrac{-5}{11}.\dfrac{14}{15}+\dfrac{-5}{11}.\dfrac{12}{15}-\dfrac{-5}{11}\)
\(=\dfrac{5}{11}.\dfrac{-14}{15}+\dfrac{5}{11}.\dfrac{-12}{15}+\dfrac{5}{11}\)
\(=\dfrac{5}{11}.\left(\dfrac{-14}{15}+\dfrac{-12}{15}+1\right)\)
\(=\dfrac{5}{11}.\dfrac{-11}{15}=\dfrac{-1}{3}\)
e, \(\dfrac{13}{47}.\dfrac{1}{8}+\dfrac{13}{47}.\dfrac{1}{2}+\dfrac{13}{47}.\dfrac{-13}{8}-\dfrac{34}{47}\)
\(=\dfrac{13}{47}.\left(\dfrac{1}{8}+\dfrac{1}{2}+\dfrac{-13}{8}\right)-\dfrac{34}{47}\)
\(=\dfrac{13}{47}.\left(-1\right)-\dfrac{34}{47}\)
\(=\dfrac{-13}{47}-\dfrac{34}{47}=-1\)
\(#WendyDang\)
