\(\frac{3}{7}-\frac{4}{7}:\left(x-1\right)=\frac{-5}{7}\)
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1,\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{3}{7}.\left(7-\frac{1}{6}\right)+\frac{1}{3}\)
\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{3}{7}.\frac{41}{6}+\frac{1}{3}\)
\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{41}{14}+\frac{1}{3}\)
\(\frac{2}{9}.\left(x-\frac{9}{4}\right)+\frac{1}{2}=\frac{137}{42}\)
\(\frac{2}{9}.\left(x-\frac{9}{4}\right)=\frac{137}{42}-\frac{1}{2}\)
\(\frac{2}{9}.\left(x-\frac{9}{4}\right)=\frac{58}{21}\)
\(\left(x-\frac{9}{4}\right)=\frac{5}{2}:\frac{2}{9}\)
\(\left(x-\frac{9}{4}\right)=\frac{45}{4}\)
\(x=\frac{45}{4}+\frac{9}{4}\)
\(x=\frac{27}{2}\)
`Answer:`
Ta thấy:
\(9=1.9\)
\(20=10.2\)
\(33=11.3\)
...
\(9200=100.92\)
`=>` Mẫu thức của từng nhân tử có dạng là \(n\left(n+8\right)\)
Xét dạng tổng quát của nhân tử: \(1+\frac{7}{n\left(n+8\right)}=\frac{n^2+8n+7}{n\left(n+8\right)}=\frac{\left(n+1\right)\left(n+7\right)}{n\left(n+8\right)}\)
\(n=1\Rightarrow1+\frac{7}{1.9}=\frac{2.8}{1.9}\)
\(n=2\Rightarrow1+\frac{7}{2.10}=\frac{3.9}{2.10}\)
\(n=3\Rightarrow1=\frac{7}{3.10}=\frac{4.10}{3.11}\)
...
\(n=92\Rightarrow1+\frac{7}{92.100}=\frac{93.99}{92.100}\)
\(\Rightarrow\frac{2.8}{1.9}.\frac{3.9}{2.10}.\frac{4.10}{3.11}...\frac{93.99}{92.100}=\frac{\left(2.3.4...93\right)\left(8.9.10...9\right)}{\left(1.2.3...92\right)\left(9.10.11...100\right)}=\frac{93.8}{1.100}=\frac{186}{25}\)
\(B=4\cdot\left(-\frac{1}{2}\right)^3:\left(\frac{4}{5}\right)^0\cdot\frac{1}{2}-\frac{\frac{3}{5}-\frac{3}{9}+\frac{3}{13}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{13}}\)
\(=4\cdot\frac{-1}{8}:1\cdot\frac{1}{2}-\frac{3\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{13}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{13}\right)}\)
\(=-\frac{1}{4}-\frac{3}{7}=-\frac{19}{28}\)
\(\frac{3}{7}-\frac{4}{7}:\left(x-1\right)=\frac{-5}{7}\)
\(\frac{4}{7}:\left(x-1\right)=\frac{3}{7}-\left(\frac{-5}{7}\right)=\frac{8}{7}\)
\(x-1=\frac{4}{7}:\frac{8}{7}\)
\(x-1=\frac{1}{2}\)
=> \(x=\frac{1}{2}+1=\frac{3}{2}\)
Vậy x= \(\frac{3}{2}\)
Chúc bạn học tốt !
\(\frac{3}{7}-\frac{4}{7}:\left(x-1\right)=-\frac{5}{7}\)
\(\Leftrightarrow\frac{4}{7}:\left(x-1\right)=\frac{3}{7}-\left(-\frac{5}{7}\right)\)
\(\Leftrightarrow\frac{4}{7}:\left(x-1\right)=\frac{8}{7}\)
\(\Leftrightarrow x-1=\frac{4}{7}:\frac{8}{7}\)
\(\Leftrightarrow x-1=\frac{1}{2}\)
\(\Leftrightarrow x=1\frac{1}{2}\)
Vậy: \(x=1\frac{1}{2}\)