Đáp án:
a)$\frac{9^4.27^5.3^6.3^4}{3^8.81^4.234.8^2}$ =$\frac{3^8.3^{15}.3^6.3^4}{3^8.3^{16}.(3^2.26).64}$= $\frac{3^{33}}{3^{26}.26.64}$= $\frac{3^7}{1664}$= $\frac{2187}{1664}$
b)N=$\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}$ =$\frac{2^{12}.3^{10}+(2.3)^9.(2^3.3.5)}{2^{12}.3^{12}-(2.3)^{11}}$= $\frac{2^{12}.3^{10}+2^{12}.3^{10}.5}{2^{12}.3^{12}-2^{11}.3^{11}}$= $\frac{2^{12}.3^{10}(1+5)}{2^{11}.3^{11}(2.3-1)}$= $\frac{2.6}{3.5}$= $\frac{4}{5}$
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