Giải thích các bước giải:
$\dfrac{5\cdot 4^{15}\cdot 9^9-4\cdot 3^{20}\cdot 8^9}{5\cdot 2^9\cdot 6^{19}-7\cdot 2^{29}\cdot 27^6}$
$=\dfrac{5\cdot (2^2)^{15}\cdot (3^2)^9-4\cdot 3^{20}\cdot (2^3)^9}{5\cdot 2^9\cdot (2\cdot 3)^{19}-7\cdot 2^{29}\cdot (3^3)^6}$
$=\dfrac{5\cdot 2^{30}\cdot 3^{18}-4\cdot 3^{20}\cdot 2^{27}}{5\cdot 2^9\cdot 2^{19}\cdot 3^{19}-7\cdot 2^{29}\cdot 3^{18}}$
$=\dfrac{5\cdot 2^{30}\cdot 3^{18}-2^2\cdot 3^{20}\cdot 2^{27}}{5\cdot 2^{28}\cdot 3^{19}-7\cdot 2^{29}\cdot 3^{18}}$
$=\dfrac{5\cdot 2^{30}\cdot 3^{18}- 3^{20}\cdot 2^{29}}{5\cdot 2^{28}\cdot 3^{19}-7\cdot 2^{29}\cdot 3^{18}}$
$=\dfrac{2^{29}\cdot 3^{18}(5\cdot 2- 3^{2})}{2^{28}\cdot 3^{18}\cdot (5\cdot 3-2\cdot 7)}$
$=\dfrac{2^{29}\cdot 3^{18}\cdot 1}{2^{28}\cdot 3^{18}\cdot 1}$
$=2$
