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1: \(\dfrac{-7}{4}\cdot\dfrac{2}{9}=\dfrac{-14}{36}=\dfrac{-7}{18}\)
2: \(=\dfrac{12}{13}\cdot\dfrac{26}{5}=\dfrac{24}{5}\)
3: \(=\dfrac{20}{11}\cdot\dfrac{55}{21}=\dfrac{100}{21}\)
4: \(=\dfrac{-40}{240}=\dfrac{-1}{6}\)
Bài 1:
a) \(\dfrac{65}{91}+\dfrac{-33}{55}=\dfrac{5}{7}+\dfrac{-3}{5}=\dfrac{25}{35}+\dfrac{-21}{35}=\dfrac{4}{35}\)
b) \(\dfrac{36}{-84}+\dfrac{100}{450}=\dfrac{-3}{7}+\dfrac{2}{9}=\dfrac{-27}{63}+\dfrac{14}{63}=\dfrac{-13}{63}\)
=\(\dfrac{1.\left(-1\right).\left(-3\right).\left(-2\right)}{1.2.1.2}\)
\(=\dfrac{-6}{4}\)
\(=-\dfrac{3}{4}\)
\(\cdot DuyNam\)
`a, -5/6; -3/4; 7/24; 7/8; 16/17`
`b, 205/107; 20/23; 214/315; -5/8; -16/19`
\(\dfrac{-15}{3}.\dfrac{26}{7}.\dfrac{-21}{5}.\dfrac{15}{16}\)
\(=5.\dfrac{2.13}{7}.\dfrac{3.7}{5}.\dfrac{3.5}{2.8}\)
\(=\dfrac{5.13.3.3}{4}=\dfrac{585}{4}\)
E = \(\left(16.64\right)^3.16^5.84^2\)
\(=16^3.64^3.16^5.84^2\)
\(=16^8.\left(4^3\right)^3.84^2\)
\(=4^{16}.4^9.7^2.12^2\)
\(=4^{16}.4^9.7^2.3^2.4^2\)
\(=4^{26}.49.9\)