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\(=\dfrac{5\cdot2^{30}-3^{20}\cdot2^{29}}{5\cdot2^{10}-7\cdot2^{30}\cdot3^3}\)
\(=\dfrac{2^{29}\left(5\cdot2-3^{20}\right)}{2^{10}\left(5\cdot1-7\cdot2^{20}\cdot3^3\right)}=\dfrac{2^{19}\cdot\left(10-3^{20}\right)}{5-189\cdot2^{20}}\)
Rút gọn các biểu thức sau:
E = \(\dfrac{9.5^{20}.27^9-3.9^{15}.25^9}{7.3^{29}.125^6-3.3^9.15^{19}}\)
\(=\dfrac{3^2\cdot5^{20}\cdot3^{27}-3\cdot3^{30}\cdot5^{18}}{7\cdot3^{29}\cdot5^{13}-3^{29}\cdot5^{19}}=\dfrac{3^{29}\cdot5^{20}-5^{18}\cdot3^{31}}{3^{29}\cdot5^{13}\cdot7-3^{29}\cdot5^{19}}\)
\(=\dfrac{3^{29}\cdot5^{18}\left(5^2-3^2\right)}{3^{29}\cdot5^{13}\left(7-5^6\right)}=5^5\cdot\dfrac{4^2}{7-5^6}\)
\(=\dfrac{2^{12}\cdot3^{10}+2^9\cdot2^3\cdot3^9\cdot3\cdot5}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}\)
\(=\dfrac{2^{12}\cdot3^{10}+2^{12}\cdot3^{10}\cdot5}{2^{11}\cdot3^{11}\cdot5}\)
\(=\dfrac{2^{12}\cdot3^{10}\cdot6}{2^{11}\cdot3^{11}\cdot5}=\dfrac{2\cdot6}{3\cdot5}=\dfrac{12}{15}=\dfrac{4}{5}\)
\(\left(\dfrac{1}{9}\right)^x=\left(\dfrac{1}{27}\right)^6\)
\(\Rightarrow\left(3^{-2}\right)^x=\left(3^{-3}\right)^6\)
\(\Rightarrow3^{-2x}=3^{-18}\)
\(\Rightarrow-2x=-18\)
\(\Rightarrow x=9\)
Vậy \(x=9\)
\(\left(\dfrac{1}{9}\right)^x=\left(\dfrac{1}{27}\right)^6\)
\(3^{-2x}=3^{-18}\)
=>\(-2x=-18\)
=>\(x=9\)
Vậy...