Question

[Nguyễn Thị Khánh Huyền]

1.thực hiện phép tính

a.\(\dfrac{-5}{21}-\dfrac{1}{3}+3\dfrac{1}{2}.\left(\dfrac{-2}{3}\right)^3\)

b)\(-2\dfrac{1}{3}+\left(\dfrac{3}{8}-\dfrac{3}{4^{^{ }}}\right)^3:\dfrac{5}{9}-\dfrac{1}{2}\)

c)\(\left(6-2\dfrac{4}{5}\right).3\dfrac{1}{8}-1\dfrac{3}{5}:\left(-\dfrac{1}{2}\right)^2\)

d)\(-\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{7}.\dfrac{-1}{3}-\left(0,5\right)^3\)

e)\(\dfrac{15}{5}-\dfrac{2}{17}+\dfrac{15}{23}-\dfrac{15}{17}+\dfrac{4}{19}\)

Giúp mik nha mai mik phải nộp bài cho thầy rùi nì

Answer 1

[Mặc Chinh Vũ]

\(a)\dfrac{-5}{21}-\dfrac{1}{3}+3\dfrac{1}{2}.\left(\dfrac{-2}{3}\right)^3\)

\(=\dfrac{-5}{21}+\dfrac{-7}{21}+\dfrac{7}{2}.\dfrac{-8}{27}\)

\(=-\dfrac{4}{7}+\dfrac{-28}{27}\)

\(=\dfrac{-108}{189}+\dfrac{-196}{189}\)

\(=-\dfrac{304}{189}\)

Answer 2

[Mặc Chinh Vũ]

\(b)-2\dfrac{1}{3}+\left(\dfrac{3}{8}-\dfrac{3}{4}\right)^3:\dfrac{5}{9}-\dfrac{1}{2}\)

\(=-\dfrac{7}{3}+\left(\dfrac{3}{8}-\dfrac{6}{8}\right)^3.\dfrac{9}{5}-\dfrac{1}{2}\)

\(=-\dfrac{7}{3}+\left(-\dfrac{3}{8}\right)^3.\dfrac{9}{5}-\dfrac{1}{2}\)

\(=-\dfrac{7}{3}+\dfrac{-27}{512}.\dfrac{9}{5}-\dfrac{1}{2}\)

\(=-\dfrac{7}{3}+\dfrac{-243}{2560}-\dfrac{1}{2}\)

\(=\dfrac{-17920}{7680}+\dfrac{-729}{7680}+\dfrac{-3840}{7680}\)

\(=\dfrac{-22489}{7680}\)