Đáp án:
$A=\dfrac{1}{3}$
Giải thích các bước giải:
$A=\dfrac{2.6^9-4^5.9^4}{2^{10}.3^8+6^8.20}\\
=\dfrac{2.(2.3)^9-(2^2)^5.(3^2)^4}{2^{10}.3^8+(2.3)^8.(2^2.5)}\\
=\dfrac{2.2^9.3^9-2^{10}.3^8}{2^{10}.3^8+2^8.3^8.2^2.5}\\
=\dfrac{2^{10}.3^9-2^{10}.3^8}{2^{10}.3^8+2^{10}.3^8.5}\\
=\dfrac{2^{10}.3^8(3-1)}{2^{10}.3^8\left (1+5 \right )}\\
=\dfrac{2}{6}=\dfrac{1}{3}$