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1/
a, \(A=\dfrac{2}{3}+\dfrac{3}{4}.\left(-\dfrac{4}{9}\right)=\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}\)
b, \(B=2\dfrac{3}{11}.\dfrac{11}{12}.\left(-2,2\right)=\dfrac{25}{11}.\dfrac{11}{12}.\left(-\dfrac{11}{5}\right)=-\dfrac{55}{12}\)
c, \(C=\left(\dfrac{3}{4}-0,2\right):\left(0,4-\dfrac{4}{5}\right)=\left(\dfrac{3}{4}-\dfrac{1}{5}\right):\left(\dfrac{2}{5}-\dfrac{4}{5}\right)=\dfrac{11}{20}:\left(-\dfrac{2}{5}\right)=-\dfrac{11}{8}\)
2/
a, \(\dfrac{11}{12}-x=\dfrac{2}{3}+\dfrac{1}{4}\\ \Rightarrow\dfrac{11}{12}-x=\dfrac{11}{12}\\ \Rightarrow x=0\)
b, \(2x\left(x-\dfrac{1}{7}\right)=0\\ \Leftrightarrow\left\{{}\begin{matrix}2x=0\\x-\dfrac{1}{7}=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=0\\x=\dfrac{1}{7}\end{matrix}\right.\)
c, \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\\ \Rightarrow\dfrac{1}{4}:x=-\dfrac{7}{20}\\ \Rightarrow x=-\dfrac{5}{7}\)
Trả lời:
\(B=\frac{0,75-30\%+\frac{3}{7}+\frac{3}{13}}{2,75-2,2+1\frac{4}{7}+3\frac{2}{3}}\)
\(B=\frac{\frac{3}{4}-\frac{3}{10}+\frac{3}{7}+\frac{3}{13}}{\frac{11}{4}-\frac{11}{5}+\frac{11}{7}+\frac{11}{3}}\)
\(B=\frac{2019}{1820}\div\frac{2431}{420}\)
\(B=\frac{2019}{1820}\times\frac{420}{2431}\)
\(B=\frac{6057}{31603}\)
Câu 2:
1: =>x-1=5 hoặc x-1=-5
=>x=-4 hoặc x=6
2: =>|x-2|=6,75-0,75=6
=>x-2=6 hoặc x-2=-6
=>x=-4 hoặc x=8
4: =>|x|=22,5
=>x=22,5 hoặc x=-22,5
PT \(\Leftrightarrow\left[{}\begin{matrix}0,1-x=2,1\\x-0,1=2,1\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=2,2\end{matrix}\right.\)
Vậy ...
=43/306:599/105x1473/1820
=1505/61098x1473/1820
=0.01993613035
a, \(\dfrac{3}{7}\)\(x\) - 0,4 = - \(\dfrac{17}{35}\)
\(\dfrac{3}{7}\)\(x\) = - \(\dfrac{17}{35}\) + 0,4
\(\dfrac{3}{7}\)\(x\) = - \(\dfrac{3}{35}\)
\(x\) = - \(\dfrac{3}{35}\): \(\dfrac{3}{7}\)
\(x\) = - \(\dfrac{1}{5}\)
b, 0,2.(\(x\) - 3) +2,4 = 10
0,2.(\(x\) - 3) = 10 - 2,4
0,2.(\(x\) - 3) = 7,6
\(x\) - 3 = 7,6:0,2
\(x\) - 3 = 38
\(x\) = 38 + 3
\(x\) = 41
\(\frac{2}{3}\left|x\right|-\frac{1}{2}=2,2\)
\(\frac{2}{3}\left|x\right|=\frac{11}{5}+\frac{1}{2}\)
\(\frac{2}{3}\left|x\right|=\frac{22}{10}+\frac{5}{10}\)
\(\frac{2}{3}\left|x\right|=\frac{27}{10}\)
\(\left|x\right|=\frac{27}{10}:\frac{2}{3}\)
\(\left|x\right|=\frac{81}{20}\)
\(\orbr{\begin{cases}x=\frac{81}{20}\\x=-\frac{81}{20}\end{cases}}\)
Vậy x= 81/20 hoặc x= -81/20