Ôn tập toán 6

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Hoa Thạch Thảo

Bài 1 : Tính

a) \(\dfrac{5}{3}+\dfrac{3}{-4}+\dfrac{7}{6}\)

b) \(\dfrac{-1}{5}+\dfrac{5}{3}+\dfrac{-3}{2}\)

c) \(\dfrac{2}{7}+\dfrac{-7}{5}+\dfrac{-2}{35}\)

d) 3+\(\dfrac{-7}{2}+\dfrac{-1}{5}\)

Nhanh lên chiều nay mik hok rồi !!!!

Cô Bé Yêu Đời
9 tháng 3 2017 lúc 12:05

a) \(\dfrac{5}{3}+\dfrac{3}{-4}+\dfrac{7}{6}\) \(\left(MC:12\right)\)

\(=\dfrac{20}{12}+\dfrac{-9}{12}+\dfrac{14}{12}\)

\(=\dfrac{20+\left(-9\right)+14}{12}\)

\(=\dfrac{25}{12}\)

b) \(\dfrac{-1}{5}+\dfrac{5}{3}+\dfrac{-3}{2}\) \(\left(MC:30\right)\)

\(=\dfrac{-6}{30}+\dfrac{50}{30}+\dfrac{-45}{30}\)

\(=\dfrac{\left(-6\right)+50+\left(-45\right)}{30}\)

\(=\dfrac{-1}{30}\)

c) \(\dfrac{2}{7}+\dfrac{-7}{5}+\dfrac{-2}{35}\) \(\left(MC:35\right)\)

\(=\dfrac{10}{35}+\dfrac{-49}{35}+\dfrac{-2}{35}\)

\(=\dfrac{10+\left(-49\right)+\left(-2\right)}{35}\)

\(=\dfrac{-41}{35}\)

d) \(3+\dfrac{-7}{2}+\dfrac{-1}{5}\) \(\left(MC:10\right)\)

\(=\dfrac{30}{10}+\dfrac{-35}{10}+\dfrac{-2}{10}\)

\(=\dfrac{30+\left(-35\right)+\left(-2\right)}{10}\)

\(=\dfrac{-7}{10}\)

Adorable Angel
9 tháng 3 2017 lúc 12:11

a) \(\dfrac{5}{3}+\dfrac{3}{-4}+\dfrac{7}{6}\)

\(=\dfrac{5}{3}+\dfrac{-3}{4}+\dfrac{7}{6}\)

\(=\) \(\dfrac{20}{12}+\dfrac{-9}{12}+\dfrac{14}{12}\)

\(=\dfrac{11}{12}+\dfrac{14}{12}\)

\(=\dfrac{25}{12}\)

b) \(\dfrac{-1}{5}+\dfrac{5}{3}+\dfrac{-3}{2}\)

\(=\dfrac{-6}{30}+\dfrac{50}{30}+\dfrac{-45}{30}\)

\(=\dfrac{44}{30}+\dfrac{-45}{30}\)

\(=\dfrac{-1}{30}\)

c) \(\dfrac{2}{7}+\dfrac{-7}{5}+\dfrac{-2}{35}\)

\(=\dfrac{10}{35}+\dfrac{-49}{35}+\dfrac{-2}{35}\)

\(=\dfrac{-39}{35}+\dfrac{-2}{35}\)

\(=\dfrac{-41}{35}\)

d) \(3+\dfrac{-7}{2}+\dfrac{-1}{5}\)

\(=\dfrac{3}{1}+\dfrac{-7}{2}+\dfrac{-1}{5}\)

\(=\dfrac{30}{10}+\dfrac{-35}{10}+\dfrac{-2}{10}\)

\(=\dfrac{-5}{10}+\dfrac{-2}{10}\)

\(=\dfrac{-7}{10}\)

Quìn
9 tháng 3 2017 lúc 11:44

a) \(\dfrac{5}{3}+\dfrac{3}{-4}+\dfrac{7}{6}=\dfrac{25}{12}\)
b) \(\dfrac{-1}{5}+\dfrac{5}{3}+\dfrac{-3}{2}=\dfrac{-1}{30}\)
c) \(\dfrac{2}{7}+\dfrac{-7}{5}+\dfrac{-2}{35}=\dfrac{-41}{35}\)
d) \(3+\dfrac{-7}{2}+\dfrac{-1}{5}=\dfrac{-7}{10}\)


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