Đáp án: $A = \frac{1}{3}$
Giải thích các bước giải:
$A = \frac{2.6^{9} - 4^{5}.9^{4}}{2^{10}.3^{8} + 6^{8}.20} = \frac{2.(2.3)^{9} - (2.2)^{5}.(3.3)^{4}}{2^{10}.3^{8} + (2.3)^{8}.2².5} = \frac{2.2^{9}.3^{9} - 2^{5}.2^{5}.3^{4}3^{4}}{2^{10}.3^{8} + 2².2^{8}3^{8}.5} =\frac{3.2^{10}.3^{8} - 1.2^{10}.3^{8}}{1.2^{10}.3^{8} + 5.2^{10}.3^{8}} = \frac{(3 - 1).2^{10}.3^{8}}{(1 + 5).2^{10}.3^{8}} = \frac{2}{6} = \frac{1}{3}$