\(A=\frac{21^2.14.125}{35^5.6}=\frac{3^2.7^2.7.2.5^3}{5^5.7^5.6}=\frac{3^2.7^3.2.5^3}{5^5.7^5.2.3}=\frac{3}{5^2.7^2}=\frac{3}{1225}\)

\(\frac{21^2.14.125}{35^5.6}=\frac{\left(3.7\right)^2.7.2.5^3}{\left(5.7\right)^5.2.3}=\frac{3^2.7^2.7.2.5^3}{5^5.7^5.2.3}\)

\(=\frac{3^2.7^3.2.5^3}{5^5.7^5.2.3}=\frac{3.1.1.1}{5^2.7^2.1.1}\)

\(=\frac{3}{35^2}=\frac{3}{1225}\)

G=(21².14.125):35⁵.6

=\(\frac{\left(3.7\right)^2.7.2.5^{^3}}{\left(7.5\right)^5.2.3}\)=\(\frac{3^2.7^2.7.5^3}{7^5.5^5.3}\)=\(\frac{3}{7^2.5^2}\)=\(\frac{3}{49.25}\)=\(\frac{3}{1225}\)

\(G=\frac{21^2.14.125}{35^5.6}\)

\(G=\frac{\left(3.7\right)^2.7.2.5^3}{\left(7.5\right)^5.2.3}=\frac{3}{7^2.5^2}=\frac{3}{49.25}=\frac{3}{1225}\)

bn biết làm phần H k

=\(\frac{-20}{21}.\left(\frac{22}{35}+\frac{13}{35}\right)+\frac{-22}{21}\)

=\(\frac{-20}{21}.\left(\frac{35}{35}\right)+\frac{-22}{21}\)

=\(\frac{-20}{21}+\frac{-22}{21}\)

=\(\frac{-42}{21}\)=-2

\(\frac{7}{3.4}-\frac{9}{4.5}+\frac{11}{5.6}-\frac{13}{6.7}+\frac{15}{7.8}-\frac{17}{8.9}-\frac{19}{9.10}+\frac{21}{10.11}\)

\(=\frac{3+4}{3.4}-\frac{4+5}{4.5}+\frac{5+6}{5.6}-\frac{6+7}{6.7}+\frac{7+8}{7.8}-\frac{8+9}{8.9}-\frac{9+10}{9.10}+\frac{10+11}{10.11}\)

\(=\frac{1}{3}+\frac{1}{4}-\frac{1}{4}-\frac{1}{5}+\frac{1}{5}+\frac{1}{6}-\frac{1}{6}-\frac{1}{7}+\frac{1}{7}+\frac{1}{8}-\frac{1}{8}-\frac{1}{9}+\frac{1}{9}+\frac{1}{10}-\frac{1}{10}-\frac{1}{11}\)

\(=\frac{1}{3}-\frac{1}{11}=\frac{8}{33}\)

đây là toán lớp 6 ư tui chưa học đấy

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