Đáp án:
a) `0`
b) `13/4800`
c) `9/5`
d) `17,3`
e) `(-187)/70`
Giải thích các bước giải:
a) $9 . \bigg(\dfrac{-1}{3}\bigg)^3 + \dfrac{1}{3}\\=9 . \dfrac{-1}{27} + \dfrac{1}{3}\\= \dfrac{-1}{3}+ \dfrac{1}{3}=0$
b) $\bigg(1+ \dfrac{1}{3} - \dfrac{1}{4}\bigg).\bigg(\dfrac{4}{5} - \dfrac{3}{4}\bigg)^2\\= \bigg(\dfrac{12}{12}+ \dfrac{4}{12}-\dfrac{3}{12}\bigg).\bigg(\dfrac{16}{20}-\dfrac{15}{20}\bigg)^2\\=\dfrac{13}{12}.\bigg(\dfrac{1}{20}\bigg)^2\\= \dfrac{13}{12} . \dfrac{1}{400}=\dfrac{13}{4800}$
c) $\dfrac{9}{7}+\dfrac{4}{5}-\dfrac{2}{7}\\=\dfrac{45}{35}+ \dfrac{28}{35}-\dfrac{10}{35}\\=\dfrac{63}{35} = \dfrac{9}{5}$
d) $\bigg(\dfrac{7}{2}-2.\dfrac{1}{3}\bigg): \dfrac{1}{6}+0,3\\=\bigg(\dfrac{7}{2}- \dfrac{2}{3}\bigg).6 +0,3\\= \bigg(\dfrac{21}{6}-\dfrac{4}{6}\bigg).6+0,3\\= \dfrac{17}{6}.6 + 0,3\\= 17 + 0,3 = 17,3$
e) $\dfrac{3}{7}+ \bigg(\dfrac{-5}{2}\bigg) + \bigg(\dfrac{-3}{5}\bigg)\\=\dfrac{30}{70}+ \dfrac{-175}{70}+\dfrac{-42}{70}\\=\dfrac{-187}{70}$
