Giá trị của biểu thức \(A=\dfrac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\) là
\(\dfrac{4}{5}.\)\(\dfrac{5}{4}.\)\(\dfrac{22}{31}.\)\(\dfrac{11}{12}.\)Hướng dẫn giải:\(A=\dfrac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}=\dfrac{\left(2^2\right)^6.\left(3^2\right)^5+\left(2.3\right)^9.120}{\left(2^3\right)^4.3^{12}-\left(2.3\right)^{11}}\)
\(=\dfrac{2^{12}.3^{10}+2^9.3^9.120}{2^{12}.3^{12}-2^{11}.3^{11}}=\dfrac{2^9.3^9\left(2^3.3+120\right)}{2^{11}.3^{11}.\left(2.3-1\right)}\)
\(=\dfrac{2^9.3^9.144}{2^{11}.3^{11}.5}=\dfrac{144}{2^2.3^2.5}=\dfrac{144}{180}=\dfrac{4}{5}.\)
