\(A=\dfrac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}\)
\(=\dfrac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}\)
\(=\dfrac{4^5.3^8-2.2^9.3^9}{2^{10}.3^8+2^8.3^8.2^2.5}\)
\(=\dfrac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}\)
\(=\dfrac{2^{10}.3^8\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}\)
\(=\dfrac{-2}{6}=\dfrac{-1}{3}\)
\(A=\dfrac{\left(2^2\right)^5.\left(3^2\right)^4-2.\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}=\dfrac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}=\dfrac{2^{10}.3^8.\left(1-3\right)}{2^{10}.3^8.\left(1+5\right)}=\dfrac{-2}{6}=-\dfrac{1}{3}\)
\(A=\dfrac{4^5.9^4-2.6^9}{2^{10}3^8+6^8.20}\)
\(A=\dfrac{\left(2^2\right)^5.\left(3^2\right)^4-2\left(2.3\right)^9}{2^{10}.3^8+\left(2.3\right)^8.2^2.5}\)
\(A=\dfrac{4^5.3^8-2.2^9.3^9}{2^{10}.3^8+2^8.3^8.2^2.5}\)
\(A=\dfrac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}\)
\(A=\dfrac{\left(2^{10}.3^8\right)\left(1-3\right)}{\left(2^{10}.3^8\right)\left(1+5\right)}\)
\(A=-\dfrac{2}{6}=-\dfrac{1}{3}\)
Vậy \(A=-\dfrac{1}{3}\)