Câu hỏi của Jimin

Question

thực hiện phép tính:

1) $\dfrac{-1}{12}$- (2$\dfrac{5}{8}$- $\dfrac{1}{3}$)

2) -1,75 - ($\dfrac{-1}{9}$ - 2$\dfrac{1}{18}$)

3) -$\dfrac{5}{6}$ - ($-\dfrac{3}{8}$+$\dfrac{1}{10}$)

4...

Hắc Hường · Accepted Answer

Giải:

1) $\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)$

$=\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)$

$=\dfrac{-1}{12}-\dfrac{55}{24}$

$=\dfrac{-19}{8}$

2) $-1,75-\left(\dfrac{-1}{9}-2\dfrac{1}{18}\right)$

$=-\dfrac{7}{4}+\dfrac{1}{9}+2\dfrac{1}{18}$

$=-\dfrac{7}{4}+\dfrac{1}{9}+\dfrac{37}{18}$

$=\dfrac{5}{12}$

3) $-\dfrac{5}{6}-\left(-\dfrac{3}{8}+\dfrac{1}{10}\right)$

$=-\dfrac{5}{6}+\dfrac{3}{8}-\dfrac{1}{10}$

$=-\dfrac{67}{120}$

4) $\dfrac{2}{5}+\left(-\dfrac{4}{3}\right)+\left(-\dfrac{1}{2}\right)$

$=\dfrac{2}{5}-\dfrac{4}{3}-\dfrac{1}{2}$

$=-\dfrac{43}{30}$

5) $\dfrac{3}{12}-\left(\dfrac{6}{15}-\dfrac{3}{10}\right)$

$=\dfrac{3}{12}-\dfrac{6}{15}+\dfrac{3}{10}$

$=\dfrac{3}{20}$

6) $\left(8\dfrac{5}{11}+3\dfrac{5}{8}\right)-3\dfrac{5}{11}$

$=8\dfrac{5}{11}+3\dfrac{5}{8}-3\dfrac{5}{11}$

$=8+\dfrac{5}{11}+3+\dfrac{5}{8}-3-\dfrac{5}{11}$

$=8+\dfrac{5}{8}$

$=\dfrac{69}{8}$

7) $-\dfrac{1}{4}.13\dfrac{9}{11}-0,25.6\dfrac{2}{11}$

$=-\dfrac{1}{4}.13\dfrac{9}{11}-\dfrac{1}{4}.6\dfrac{2}{11}$

$=-\dfrac{1}{4}\left(13\dfrac{9}{11}+6\dfrac{2}{11}\right)$

$=-\dfrac{1}{4}\left(13+\dfrac{9}{11}+6+\dfrac{2}{11}\right)$

$=-\dfrac{1}{4}\left(13+6+1\right)$

$=-\dfrac{1}{4}.20=-5$

8) $\dfrac{4}{9}:\left(-\dfrac{1}{7}\right)+6\dfrac{5}{9}:\left(-\dfrac{1}{7}\right)$

$=\dfrac{4}{9}\left(-7\right)+6\dfrac{5}{9}\left(-7\right)$

$=-7\left(\dfrac{4}{9}+6\dfrac{5}{9}\right)$

$=-7\left(\dfrac{4}{9}+6+\dfrac{5}{9}\right)$

$=-7\left(6+1\right)$

$=-7.7=-49$

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