Cách làm cho bạn:
A= $\frac{27^{10}+9^{5}}{9^{13}+27^{2}}$
= $\frac{\left (3^{3} \right )^{10}+\left (3^{2} \right )^{5}}{\left (3^{2} \right )^{13}+\left (3^{3} \right )^{2}}$
= $\frac{3^{30}+3^{10}}{3^{26}+3^{6}}$
=$\frac{3^{10}.\left ( 3^{20}+1 \right )}{3^{6}.\left ( 3^{20}+1\right )}$
=$\frac{3^{10}}{3^{6}}$
=$3^{10-6}$
= $3^{4}=81$
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