ta có : $\frac{ 8^{10} . 3^{30}}{7^{30} . 4^{15}}$
= $\frac{ (2^{3} )^{10} . 3^{30}}{7^{30} .(2^{2} )^{15}}$
= $\frac{ 2^{30} . 3^{30}}{7^{30} . 2^{30}}$
=$\frac{3^{30}}{7^{30}}$
=$\frac{9^{15}}{7^{30}}$
vì $9^{15}$ > $4^{15}$
mà $7^{30}$ = $7^{30}$
⇒$\frac{9^{15}}{7^{30}}$ > $4^{15}$ > $4^{15}$
⇒ $\frac{ 8^{10} . 3^{30}}{7^{30} . 4^{15}}$ > $4^{15}$ > $4^{15}$
