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25 tháng 12 2015

\(16\frac{2}{7}:\left(\frac{-3}{5}\right)+28\frac{2}{7}:\frac{3}{5}\)

=\(\frac{114}{7}:\left(\frac{-3}{5}\right)+\frac{198}{7}:\frac{3}{5}\)

=\(-\frac{190}{7}+\frac{330}{7}\)

=\(\frac{-190+330}{7}=\frac{140}{7}=20\)

23 tháng 9 2017

1) \(\left|x-\frac{3}{5}\right|< \frac{1}{3}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{3}{5}< \frac{1}{3}\\x-\frac{3}{5}< -\frac{1}{3}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{1}{3}+\frac{3}{5}\\x< \frac{-1}{3}+\frac{3}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x< \frac{5}{15}+\frac{9}{15}\\x< \frac{-5}{15}+\frac{9}{15}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{14}{15}\\x< \frac{4}{15}\end{cases}}\)

                vay \(\orbr{\begin{cases}x< \frac{14}{15}\\x< \frac{4}{15}\end{cases}}\)

2) \(\left|x+\frac{11}{2}\right|>\left|-5,5\right|\)

\(\left|x+\frac{11}{2}\right|>5,5\)

\(\Rightarrow\orbr{\begin{cases}x+\frac{11}{2}>\frac{11}{2}\\x+\frac{11}{2}>-\frac{11}{2}\end{cases}}\Rightarrow\orbr{\begin{cases}x>\frac{11}{2}-\frac{11}{2}\\x>\frac{-11}{2}-\frac{11}{2}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x>0\\x>-11\end{cases}}\)

vay \(\orbr{\begin{cases}x>0\\x>-11\end{cases}}\)

3) \(\frac{2}{5}< \left|x-\frac{7}{5}\right|< \frac{3}{5}\)

\(\Rightarrow\left|x-\frac{7}{5}\right|>\frac{2}{5}\) va \(\left|x-\frac{7}{5}\right|< \frac{3}{5}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{7}{5}>\frac{2}{5}\\x-\frac{7}{5}>\frac{-2}{5}\end{cases}}\Rightarrow\orbr{\begin{cases}x>\frac{2}{5}+\frac{7}{5}\\x>\frac{-2}{5}+\frac{7}{5}\end{cases}}\)va \(\orbr{\begin{cases}x-\frac{7}{5}< \frac{3}{5}\\x-\frac{7}{5}< \frac{-3}{5}\end{cases}}\Rightarrow\orbr{\begin{cases}x< \frac{3}{5}+\frac{7}{5}\\x< \frac{-3}{5}+\frac{7}{5}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x>\frac{9}{5}\\x>1\end{cases}}\)va \(\orbr{\begin{cases}x< 2\\x< \frac{4}{5}\end{cases}}\)

vay ....

25 tháng 8 2018

Bài 1:

\(A=\left(\frac{-5}{11}+\frac{7}{22}-\frac{4}{33}-\frac{5}{44}\right):\left(38\frac{1}{122}-39\frac{7}{22}\right)\)

\(=\frac{-49}{132}:\left(-\frac{879}{671}\right)=\frac{2989}{105408}\)

Bài 2:

\(\frac{4}{5}-\left(\frac{-1}{8}\right)=\frac{7}{8}-x\)

<=>  \(\frac{7}{8}-x=\frac{27}{40}\)

<=>  \(x=\frac{7}{8}-\frac{27}{40}=\frac{1}{5}\)

Vậy...

25 tháng 8 2018

bài 2 mình tính sai, sửa

.......

<=>  \(\frac{7}{8}-x=\frac{37}{40}\)

<=>  \(x=\frac{7}{8}-\frac{37}{40}=\frac{-1}{20}\)

Vậy....

14 tháng 9 2017

a) \(\frac{1}{3}-\left(\frac{1}{2}+\frac{1}{8}\right)\)

=   \(\frac{1}{3}-\left(\frac{4}{8}+\frac{1}{8}\right)\)

=     \(\frac{1}{3}-\frac{5}{8}\)

\(\frac{8}{24}-\frac{15}{24}\)

\(\frac{-7}{24}\)

b) \(\frac{1}{2}-\frac{1}{4}+\frac{1}{13}+\frac{1}{8}\)

\(\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{8}\right)\)\(\frac{1}{13}\)

\(\left(\frac{4}{8}-\frac{2}{8}+\frac{1}{8}\right)+\frac{1}{13}\)

=                 \(\frac{1}{8}+\frac{1}{13}\)

=                 \(\frac{13}{104}+\frac{8}{104}\)

=                        \(\frac{23}{104}\)

c) \(13\frac{2}{7}:\left(\frac{-8}{9}\right)+2\frac{5}{7}:\left(\frac{-8}{9}\right)\)

\(\left(13\frac{2}{7}+2\frac{5}{7}\right):\left(\frac{-8}{9}\right)\)

=         \(16:\left(\frac{-8}{9}\right)\)

=         -18