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a) \(2\left(2x-7\right)^2=18\)
\(\Leftrightarrow\left(2x-7\right)^2=9\)
\(\Leftrightarrow\left(2x-7\right)^2=3^2\)
\(\Leftrightarrow2x-7=3\)
\(\Leftrightarrow2x=10\)
\(\Leftrightarrow x=5\)
2.(2X-7)^2= 18
(2X-7)^2=18:2
(2x-7)^2= 9
(2x-7)^2 = 3^2 = (-3)^2
=> (2x-7)^2 = 3^2 và (2x-7)^2 = (-3)^2
\(\frac{9^{14}.25^5.8^7}{18^{12}.625^3.24^3}=\frac{\left(3^2\right)^{14}.\left(5^2\right)^5.\left(2^3\right)^7}{\left(2.3^2\right)^{12}.\left(5^4\right)^3.\left(3.2^3\right)^3}=\frac{3^{28}.5^{10}.2^{21}}{2^{12}.3^{24}.5^{12}.3^3.2^9}=\frac{3^{28}.5^{10}.2^{21}}{2^{21}.3^{27}.5^{12}}=\frac{3}{5^2}=\frac{3}{25}\)
\(\frac{9^{14}.25^5.8^2.8^7}{18^{12}.625^3.24^3}=\frac{3^{28}.5^{10}.8^9}{2^{12}.9^{12}.5^{12}.3^3.2^9}\)\(=\frac{3^{28}.5^{10}.2^{27}}{2^{21}.5^{12}.3^{24}.3^3}=\frac{3^{28}.5^{10}.2^{27}}{2^{21}.5^{12}.3^{27}}\) \(=\frac{3.2^6}{5^2}=\frac{192}{25}=7,68\)