Bài 13 (SGK tập 1 - Trang 12)

Gửi bởi: Sách Giáo Khoa Vào 26 tháng 12 2018 lúc 11:14:00

Câu hỏi

Tính:
a) \(\dfrac{-3}{4}.\dfrac{12}{-5}.\left(-\dfrac{25}{6}\right);\) b) \(\left(-2\right).\dfrac{-38}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right);\)
c) \(\left(\dfrac{11}{12}:\dfrac{33}{16}\right).\dfrac{3}{5};\) d) \(\dfrac{7}{23}.\left[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}\right].\)

Hướng dẫn giải

a, \(\dfrac{-3}{4}.\dfrac{12}{-5}.\left(-\dfrac{25}{6}\right)=\dfrac{9}{5}.\left(-\dfrac{25}{6}\right)=-\dfrac{15}{2}\)

b,\(\left(-2\right).\dfrac{-38}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right)=\dfrac{76}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right)=-\dfrac{19}{3}.\left(-\dfrac{3}{8}\right)=\dfrac{19}{8}\)

c,\(\left(\dfrac{11}{12}:\dfrac{33}{16}\right).\dfrac{3}{5}=\dfrac{4}{9}.\dfrac{3}{5}=\dfrac{4}{15}\)

d, \(\dfrac{7}{23}.\left[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}\right]=\dfrac{7}{23}.\left(-\dfrac{13}{6}\right)=-\dfrac{91}{138}\)

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