\(\frac{3^{10}+6^2}{5\cdot3^8+20}\)   

\(=\frac{3^{10}+\left(3 \cdot2\right)^2}{5\cdot3^8+5\cdot4}\)   

\(=\frac{3^{10}+3^2\cdot2^2}{5\cdot\left(3^8+4\right)}\)   

\(=\frac{3^2\cdot\left(3^8+2^2\right)}{5\cdot\left(3^8+4\right)}\)   

\(=\frac{3^2\cdot\left(3^8+4\right)}{5\cdot\left(3^8+4\right)}\)   

\(=\frac{3^2}{5}\)   

\(=\frac{9}{5}\)

đáp án là 9/5

\(\frac{3^{10}+6^2}{5.3^8+20}=\frac{3^2+6^2}{5+20}=\frac{9^2}{25}=\frac{81}{25}=\frac{9}{5}\)

\(\frac{3^{10}+6^2}{5\cdot3^8+20}\)   

\(=\frac{3^{10}+\left(3\cdot2\right)^2}{5\left(3^8+4\right)}\)   

\(=\frac{3^{10}+3^2\cdot2^2}{5\left(3^8+4\right)}\)   

\(=\frac{3^2\left(3^8+4\right)}{5\left(3^8+4\right)}\)   

\(=\frac{9}{5}\)

\(\frac{3^{10}+6^2}{5.3^8+20}\)\(=\frac{3^2+2^2.3^2}{5+2^2.5}=\frac{3^2\left(1+2^2\right)}{5\left(1+2^2\right)}\)\(=\frac{3^2}{5}\)\(=\frac{9}{5}\)

\(a.\frac{3}{28}\)

\(b.\frac{9}{5}\)

Bây giờ mình sẽ viết đầy đủ hơn nhé:

a) \(\frac{28^{15}.3^{17}}{84^{16}}=\frac{\left(28.3\right)^{15}.3^2}{\left(28.3\right)^{15}.84}=\frac{9}{84}=\frac{3}{28}\)

b)\(\frac{3^{10}+6^2}{5.3^8+20}=\frac{3^{10}+2^2.3^2}{5.3^8+20}=\frac{3^2.\left(3^8+2^2\right)}{5.\left(3^8+2^2\right)}\)\(=\frac{9}{5}\)

a) \(\frac{28^{15}.3^{17}}{84^{16}}=\frac{\left(2^2.7\right)^{15}.3^{17}}{\left(2^2.3.7\right)^{16}}=\frac{2^{30}.7^{15}.3^{17}}{2^{32}.3^{16}.7^{16}}=\frac{3}{2^2.7}=\frac{3}{28}\)

b) \(\frac{3^{10}+6^2}{5.3^8+20}=\frac{3^{10}+\left(2.3\right)^2}{5.3^9+2^2.5}=\frac{3^{10}+2^2.3^2}{5\left(3^8.2^2\right)}=\frac{3^2.\left(3^8+2^2\right)}{5.\left(3^8+2^2\right)}=\frac{3^2}{5}=\frac{9}{5}\)