1 trừ 2 phần 7 trừ 1 phần 4
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viết rõ lại cái đề giùm tui tui mới làm được
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\(\frac{6}{7}+\frac{2}{5}-\frac{1}{2}+2\frac{38}{91}-\frac{4}{5}=\frac{27300}{31850}+\frac{12740}{31850}-\frac{15925}{31850}+\) \(2\frac{13300}{31850}\)\(-\frac{25480}{31850}\)
\(=2\frac{27300+12740-15925+13300-25480}{31850}\)\(=2\frac{341}{910}\)
HỌC TỐT!!!
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\(A=\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3^2}-1\right)...\left(\frac{1}{100^2}-1\right)=\frac{-3}{2^2}.\frac{-8}{3^2}...\frac{-9999}{100^2}\)
\(=-\frac{3.8...9999}{2^2.3^2...100^2}=-\frac{1.3.2.4...99.101}{2.2.3.3...100.100}=-\frac{\left(1.2....99\right).\left(3.4...101\right)}{\left(2.3...100\right).\left(2.3...100\right)}=-\frac{1.101}{100.2}=-\frac{101}{200}\)
\(< -\frac{100}{200}=\frac{1}{2}=B\)
=> A < B
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\(\dfrac{4}{5}\)+\(\dfrac{7}{10}\) -\(\dfrac{1}{2}\)
Giữ nguyên phân số \(\dfrac{7}{10}\) ( MSC: 10)
\(\dfrac{4}{5}\)= \(\dfrac{4x2}{5x2}\) =\(\dfrac{8}{10}\)
\(\dfrac{1}{2}\) = \(\dfrac{1x5}{2x5}\) = \(\dfrac{5}{10}\)
\(\dfrac{4}{5}\)+\(\dfrac{7}{10}\) -\(\dfrac{1}{2}\) = \(\dfrac{8}{10}\) +\(\dfrac{7}{10}\) -\(\dfrac{5}{10}\) =1
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a) \(\frac{2}{3}x\times\frac{1}{2}=\frac{1}{10}\Rightarrow\frac{2}{3}x=\frac{1}{5}\Rightarrow x=\frac{3}{10}\)
\(1-\dfrac{2}{7}-\dfrac{1}{4}=\dfrac{7}{7}-\dfrac{2}{7}=\dfrac{1}{4}=\dfrac{5}{7}-\dfrac{1}{4}=\dfrac{20}{28}-\dfrac{7}{28}=\dfrac{13}{28}\)
13/28