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a) \(\frac{1}{9.27n}=3n\)
=> \(\frac{1}{3^5n}=3n\)
=> \(\frac{1}{n}3^{-5}=3n\)
=> \(\frac{1}{n}:n=3:3^{-5}\)
=> \(n^{-2}=3^{-4}=9^{-2}\)
Vậy n=9
\(A=\frac{8\frac{3}{9}.5\frac{1}{4}+3\frac{16}{19}.5\frac{1}{4}}{\left(2\frac{14}{17}-2\frac{1}{34}\right).34}:\frac{7}{24}\)
\(=\frac{5\frac{1}{4}\left(8\frac{1}{3}+3\frac{16}{19}\right)}{\left(\frac{28}{34}-\frac{1}{34}\right).34}:\frac{7}{24}\)
\(=\frac{\frac{21}{4}\left(\frac{25}{3}+\frac{73}{19}\right)}{\frac{27}{34}.34}:\frac{7}{24}\)
\(=\frac{\frac{21}{4}\left(\frac{475}{57}+\frac{219}{57}\right)}{27}:\frac{7}{24}\)
\(=\frac{\frac{21}{4}.\frac{674}{57}}{27}:\frac{7}{24}\)
\(=\frac{\frac{14154}{228}}{27}.\frac{24}{7}=\frac{\frac{339696}{228}}{189}\)
=> không có giá trị nào của x thỏa mãn yêu cầu bài toán
Đáp án cần chọn là D
\(A=\frac{15}{34}+\frac{7}{21}+\frac{9}{34}-1\frac{15}{17}+\frac{2}{3}\)
\(=\frac{12}{17}+\frac{1}{3}-\frac{32}{17}+\frac{2}{3}\)
\(=-\frac{20}{17}+\frac{1}{3}+\frac{2}{3}\)
\(=-\frac{20}{17}+1\)
\(=-\frac{3}{17}\)
\(B=16\frac{2}{7}:\left(-\frac{3}{5}\right)-28\frac{2}{7}:\left(-\frac{3}{5}\right)\)
\(=\left(\frac{114}{7}-\frac{198}{7}\right):\left(-\frac{3}{5}\right)\)
\(=\left(-12\right):\left(-\frac{3}{5}\right)\)
\(=20\)
A\(=\frac{15}{34}+\frac{7}{21}+\frac{9}{34}-1\frac{15}{17}+\frac{2}{3}\)
\(=\left(\frac{15}{34}+\frac{9}{34}\right)+\left(\frac{7}{21}+\frac{2}{3}\right)-1\frac{15}{17}\)
\(=\left(\frac{14}{17}-\frac{15}{17}\right)+1-1\)
\(=-\frac{1}{17}\)
\(B=16\frac{2}{7}:\left(-\frac{3}{5}\right)-28\frac{2}{7}:\left(-\frac{3}{5}\right)\)
\(B=-\frac{3}{5}.\left(16\frac{2}{7}-28\frac{2}{7}\right)\)
\(B=-\frac{3}{5}.\left(-12\right)\)
\(B=\frac{36}{5}\)
Hoctot
\(\left(9\frac{2}{4}:5,2+3,4.2\frac{7}{34}\right):\left(-1\frac{9}{16}\right)\)
\(=\left(\frac{19}{2}:\frac{26}{5}+\frac{17}{5}.\frac{75}{34}\right):\left(\frac{-25}{16}\right)\)
\(=\left(\frac{19}{2}.\frac{5}{26}+\frac{17}{5}.\frac{75}{34}\right):\left(-\frac{25}{16}\right)\)
\(=\left(\frac{95}{52}+\frac{15}{2}\right).\frac{-16}{25}\)
\(=\frac{485}{52}.\left(-\frac{16}{25}\right)\)
\(=-\frac{388}{65}\)
(Bài này kết quả lớn ghê :))