a) \(\dfrac{-21}{15}\).\(\dfrac{-10}{14}\)            b)\(\left(-\dfrac{2}{3}\right)^2\)        c)\(\dfrac{-3}{4}\).\(\dfrac{-4}{5}\).\(\dfrac{16}{9}\)          d)\(\dfrac{-8}{3}\).\(\dfrac{5}{6}\)         e)\(\dfrac{16}{30}\).\(\dfrac{5}{12}\)        f) \(\dfrac{13}{30}\).\(\dfrac{-1}{5}\)                 g)\(\dfrac{2}{21}\).\(\dfrac{3}{28}\)           h)\(\left(\dfrac{-3}{4}\right)^3\)

Rút gọn rồi tính (theo mẫu).

a) \(\dfrac{21}{15}+\dfrac{2}{5}\)                      b) \(\dfrac{6}{16}+\dfrac{1}{8}\)                        c) \(\dfrac{3}{12}+\dfrac{3}{4}\)

Đ, S?

a) \(\dfrac{1}{2}-\dfrac{1}{8}=\dfrac{3}{8}\)                                  b) \(\dfrac{7}{10}-\dfrac{1}{5}=\dfrac{6}{5}\) 

c) \(\dfrac{5}{4}+\dfrac{5}{12}=\dfrac{5}{16}\)                               d) \(\dfrac{3}{6}+\dfrac{2}{3}=\dfrac{7}{6}\) 

Câu 1 :\(\dfrac{-5}{7}.\dfrac{7}{-45}\);\(\dfrac{-3}{10}.\left(-30\right)\);\(-12.\dfrac{-2}{36}\)

Câu 2: \(\dfrac{3}{4}+\dfrac{1}{8}.\dfrac{-16}{5};\dfrac{7}{15}-\dfrac{18}{21}.\dfrac{7}{9}\)

Câu 3: \(\left(\dfrac{-5}{9}+\dfrac{3}{5}\right).\dfrac{3}{10};\left(\dfrac{3}{9}-\dfrac{2}{5}\right).\dfrac{-3}{10}\)

Câu 4: \(\left(\dfrac{3}{7}+\dfrac{1}{3}\right).\left(\dfrac{1}{8}-\dfrac{1}{2}\right);\left(\dfrac{-9}{12}-\dfrac{16}{30}\right).\left(\dfrac{-18}{22}-\dfrac{6}{11}\right)\)

Càn gấp

a)\(\dfrac{2}{7}+\dfrac{-3}{8}+\dfrac{11}{7}+\dfrac{1}{7}_{ }+\dfrac{5}{-8}\)

b)\(\dfrac{3}{17}+\dfrac{-5}{13}+\dfrac{-18}{35}+\dfrac{14}{17}+\dfrac{17}{-35}_{ }+\dfrac{-8}{13}\)

c)\(\dfrac{-3}{8}+\dfrac{12}{25}+\dfrac{5}{-8}+\dfrac{2}{-5}+\dfrac{13}{25}\)

d)\(\dfrac{-5}{21}+\left(\dfrac{-16}{21}+1\right)\)

e)\(\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)

f)\(\left(\dfrac{-1}{6}+\dfrac{5}{-12}\right)+\dfrac{7}{12}\)

thực hiện phép tính

a)\(\left(\dfrac{9}{25}-2,18\right):\left(3\dfrac{4}{5}+0,2\right)\)

b)\(\dfrac{3}{8}.19\dfrac{1}{3}-\dfrac{3}{8}.33\dfrac{1}{3}\)

c)\(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)

d)\(\dfrac{2^{12}.3^5-4^6.81}{2^2.3^6+8^4.3^5}\)

e)\(4\left(-\dfrac{1}{2}\right)^2-2.\left(\dfrac{-1}{2}\right)^2+3.\left(\dfrac{-1}{2}\right)+1\)

g)\(\sqrt{\dfrac{4}{81}}:\sqrt{\dfrac{25}{81}}-1\dfrac{2}{5}\)