a) \(-\dfrac{7}{15}.\dfrac{5}{8}.\dfrac{15}{-7}.\left(-16\right)\)
\(=\dfrac{-7.5.15.\left(-16\right)}{15.8.\left(-7\right)}\)
\(=-10\)
b) \(-\dfrac{1}{2}.\left(3\dfrac{1}{5}\right)+\left(-\dfrac{1}{2}\right).\left(-2\dfrac{1}{5}\right)\)
\(=-\dfrac{1}{2}.\dfrac{16}{5}+\left(-\dfrac{1}{2}\right).\left(-\dfrac{9}{5}\right)\)
\(=-\dfrac{1}{2}\left[\dfrac{16}{5}+\left(-\dfrac{9}{5}\right)\right]\)
\(=-\dfrac{1}{2}.\dfrac{7}{5}\)
\(=-\dfrac{7}{10}\)
Tính : a)
\(=>\left(\dfrac{-7}{15}.\dfrac{15}{-7}\right).\left(\dfrac{5}{8}.\dfrac{-16}{1}\right)\)
\(=>1.\left(-10\right)\)
\(=>\left(-10\right)\)
b)\(=>\left(-\dfrac{1}{2}\right).\left(\dfrac{16}{5}\right)+\left(-\dfrac{1}{2}\right).\left(-\dfrac{11}{5}\right)\)
\(=>\left(-\dfrac{1}{2}\right).\left[\dfrac{16}{5}+\left(-\dfrac{11}{5}\right)\right]\)
\(=>-\dfrac{1}{2}.\dfrac{5}{5}\)
\(=>-\dfrac{1}{2}.1\)
\(=>-\dfrac{1}{2}\)
a)\(\dfrac{-7}{15}.\dfrac{5}{8}.\dfrac{15}{-7}.\left(-16\right)=\)
=\(\left(\dfrac{-7}{15}.\dfrac{15}{-7}\right).\dfrac{5}{8}.\left(-16\right)\)
=1.(-10)
=-10
b)\(\dfrac{-1}{2}.\left(3\dfrac{1}{5}\right)+\dfrac{-1}{2}.\left(-2\dfrac{1}{5}\right)\)=
=\(\dfrac{-1}{2}.\dfrac{16}{5}+\dfrac{-1}{2}.\dfrac{-11}{5}\)
=\(\dfrac{-1}{2}.\left(\dfrac{16}{5}+\dfrac{-11}{5}\right)\)
=\(\dfrac{-1}{2}.\dfrac{4}{5}\)
=\(\dfrac{-2}{5}\)
mình trả lời sai câu b rồi mong các bạn thông cảm
\(b..\dfrac{-1}{2}\cdot\left(3\dfrac{1}{5}-2\dfrac{1}{5}\right)\\ =\dfrac{-1}{2}\cdot1=\dfrac{-1}{2}\)
a) \(\dfrac{-7}{15}.\dfrac{5}{8}.\dfrac{15}{-7}.\left(-16\right)=\dfrac{-7}{15}.\dfrac{-15}{7}.\dfrac{5}{8}.\dfrac{-16}{1}=1.\dfrac{5.\left(-2\right)}{1.1}=1.\left(-10\right)=-10\)
b) \(\dfrac{-1}{2}.\left(3\dfrac{1}{5}\right)+\dfrac{-1}{2}.\left(-2\dfrac{1}{5}\right)=\dfrac{-1}{2}.\left[3\dfrac{1}{5}+\left(-2\dfrac{1}{5}\right)\right]=\dfrac{-1}{2}.1=\dfrac{-1}{2}\)