a)  − 52 − 71 = 52 71

b)  3 − 19 = − 3 19

c)  − 5 − 29 = 5 29

d)  57 − 43 = − 57 43

a) \(\dfrac{2}{5}=\dfrac{1}{5}\cdot\dfrac{2}{1}\)

\(\dfrac{15}{12}=\dfrac{5}{4}=\dfrac{5}{2}\cdot\dfrac{1}{2}\)

\(\dfrac{5}{-12}=\dfrac{-5}{12}=\dfrac{-5}{3}\cdot\dfrac{1}{4}\)

\(\dfrac{-3}{-4}=\dfrac{3}{4}=\dfrac{3}{2}\cdot\dfrac{1}{2}\)

Bài làm

* \(\frac{-52}{-71}=\frac{52}{71}\)( bỏ dấu " - " đi là thành phân số dương )

* \(\frac{4}{-17}=\frac{-4}{17}\)( Chuyển dấu " - " ở mẫu lên tử là được )

* \(\frac{5}{-29}=\frac{-5}{29}\)( Chuyển dấu " - " ở mẫu lên tử là được )

* \(\frac{31}{-33}=\frac{-31}{33}\)( Chuyển dấu " - " ở mẫu lên tử là được )

# Chúc bạn học tốt #

\(\frac{-71}{-52}=\frac{71}{52}\)

\(\frac{4}{-17}=\frac{-4}{17}\)

\(\frac{5}{-29}=\frac{-5}{29}\)

\(\frac{31}{-33}=\frac{-31}{33}\)

\(\dfrac{-5}{6}=\dfrac{-5\times4}{6\times4}=\dfrac{-20}{24}\)

\(\dfrac{3}{-8}=\dfrac{3\times\left(-3\right)}{-8\times\left(-3\right)}=\dfrac{-9}{24}\)

\(2=\dfrac{48}{24}\)

\(\dfrac{-25}{100}=\dfrac{-1}{4}=\dfrac{-1\times6}{4\times6}=\dfrac{-6}{24}\)

\(\dfrac{72}{108}=\dfrac{2}{3}=\dfrac{2\times8}{3\times8}=\dfrac{16}{24}\)

\(\dfrac{-15}{-17}=\dfrac{15}{17}\\ \dfrac{3}{-25}=\dfrac{-3}{25}\\ \dfrac{-1}{-5}=\dfrac{1}{5}\\ \dfrac{6}{-23}=\dfrac{-6}{23}\)

Ta có \(\dfrac{14}{15}\) = \(\dfrac{2}{3}\) : \(\dfrac{5}{7}\)

= \(\dfrac{7}{3}\) : \(\dfrac{5}{2}\)

= \(\dfrac{2}{5}\) : \(\dfrac{3}{7}\)

= \(\dfrac{7}{5}\) : \(\dfrac{3}{2}\)

\(a,-\dfrac{10}{21}=\dfrac{-2}{7}.\dfrac{5}{3}=\dfrac{-2}{3}.\dfrac{5}{7}\\ b,\dfrac{2}{21}=\dfrac{1}{3}.\dfrac{2}{7}=\dfrac{1}{7}.\dfrac{2}{3}\\ c,\dfrac{8}{15}=\dfrac{2}{3}.\dfrac{4}{5}=\dfrac{4}{3}.\dfrac{2}{5}\)

\(\dfrac{11}{16}\) = \(\dfrac{1}{16}\) + \(\dfrac{10}{16}\) = \(\dfrac{1}{16}\) + \(\dfrac{2+8}{2\times8}\) = \(\dfrac{1}{16}\) + \(\dfrac{2}{2\times8}\) + \(\dfrac{8}{2\times8}\) = \(\dfrac{1}{16}\) + \(\dfrac{1}{8}\)+ \(\dfrac{1}{2}\)

\(\dfrac{5}{12}\) = \(\dfrac{1}{12}\) + \(\dfrac{4}{12}\) = \(\dfrac{1}{12}\) + \(\dfrac{4}{3\times4}\) = \(\dfrac{1}{12}\) + \(\dfrac{1}{3}\)

\(\dfrac{6}{35}\) = \(\dfrac{1}{35}\) + \(\dfrac{5}{35}\) = \(\dfrac{1}{35}\) + \(\dfrac{5}{5\times7}\) = \(\dfrac{1}{35}\) + \(\dfrac{1}{7}\)