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3 tháng 7 2022
1: \(=\dfrac{3}{2}\cdot\dfrac{15}{49}-\dfrac{22}{15}\cdot\dfrac{5}{11}\)
\(=\dfrac{45}{98}-\dfrac{10}{15}=-\dfrac{61}{294}\)
2: =>9/20x=-71/40+105/40=34/40
=>x=17/9
13 tháng 5 2022
Bài 2:
a: \(A=11+\dfrac{3}{13}-2-\dfrac{4}{7}-5-\dfrac{3}{13}\)
\(=4-\dfrac{4}{7}=\dfrac{24}{7}\)
b: \(B=6+\dfrac{4}{9}+3+\dfrac{7}{11}-4-\dfrac{4}{9}\)
\(=5+\dfrac{7}{11}=\dfrac{62}{11}\)
c: \(C=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+1+\dfrac{5}{7}=1\)
d: \(D=\dfrac{7}{10}\cdot\dfrac{8}{3}\cdot20\cdot\dfrac{3}{8}\cdot\dfrac{5}{28}\)
\(=\dfrac{20}{10}\cdot7\cdot\dfrac{8}{3}\cdot\dfrac{3}{8}\cdot\dfrac{5}{28}=2\cdot\dfrac{5}{4}=\dfrac{5}{2}\)
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AH
Akai Haruma
Giáo viên
25 tháng 10 2021
Lời giải:
\(A=\left\{\frac{k}{2k+1}|k\in\mathbb{N}; 1\leq k\leq 4\right\}\)
17 tháng 5 2022
a: \(\left(3x-1\right)\left(-\dfrac{1}{2}x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3x-1=0\\5-\dfrac{1}{2}x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{3}\\x=10\end{matrix}\right.\)
b: \(\dfrac{2}{3}x+\dfrac{1}{2}x=\dfrac{5}{2}:\dfrac{15}{4}=\dfrac{5}{2}\cdot\dfrac{4}{15}=\dfrac{20}{30}=\dfrac{2}{3}\)
=>7/6x=2/3
hay \(x=\dfrac{2}{3}:\dfrac{7}{6}=\dfrac{2}{3}\cdot\dfrac{6}{7}=\dfrac{12}{21}=\dfrac{4}{7}\)
c: \(\left(\dfrac{44}{7}x+\dfrac{3}{7}\right)\cdot\dfrac{11}{5}=-2+\dfrac{3}{7}=-\dfrac{11}{7}\)
\(\Leftrightarrow x\cdot\dfrac{44}{7}+\dfrac{3}{7}=\dfrac{-11}{7}:\dfrac{11}{5}=\dfrac{-5}{7}\)
\(\Leftrightarrow x\cdot\dfrac{44}{7}=-\dfrac{8}{7}\)
hay \(x=-\dfrac{8}{7}:\dfrac{44}{7}=-\dfrac{2}{11}\)
15 tháng 5 2022
a: \(=\dfrac{-3}{7}\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+2+\dfrac{3}{7}=2\)
b: \(=-\dfrac{5}{7}:\left(24-\dfrac{166}{7}\right)+\dfrac{37}{3}\)
\(=-\dfrac{5}{7}:\dfrac{2}{7}+\dfrac{37}{3}=\dfrac{-5}{2}+\dfrac{37}{3}=\dfrac{59}{6}\)
c: \(=4-\dfrac{32}{27}\cdot\dfrac{-27}{8}=4+4=8\)
d: \(=\dfrac{28}{15}\cdot\dfrac{3}{4}-\dfrac{11+5}{20}\cdot\dfrac{5}{7}\)
\(=\dfrac{7}{5}-\dfrac{6}{20}\cdot\dfrac{5}{7}=\dfrac{29}{35}\)
26 tháng 4 2017
Câu 1:
a) = \(\dfrac{-7}{2}\) x \(\dfrac{45}{32}\) = \(\dfrac{-315}{64}\)
b) = \(\dfrac{18}{7}\) : \(\dfrac{-27}{14}\) = \(\dfrac{18}{7}\) x \(\dfrac{14}{-27}\) = \(\dfrac{-4}{3}\)
c) = \(\dfrac{-3}{8}\) x ( \(\dfrac{5}{11}\) + \(\dfrac{6}{11}\) + 2 ) = \(\dfrac{-3}{8}\) x 3 = \(\dfrac{-9}{8}\)
Câu 2:
\(\dfrac{-3}{5}\) . x + \(\dfrac{7}{6}\) = \(\dfrac{5}{4}\)
\(\Leftrightarrow\) \(\dfrac{-3}{5}\) . x = \(\dfrac{5}{4}\) - \(\dfrac{7}{6}\)
\(\Leftrightarrow\) \(\dfrac{-3}{5}\) . x = \(\dfrac{1}{12}\)
\(\Leftrightarrow\) x = \(\dfrac{1}{12}\) : \(\dfrac{-3}{5}\)
\(\Leftrightarrow\) x = \(\dfrac{-5}{36}\)
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