Câu a sai rồi nha haizz
[tex]\frac{2.5.5^{21}-9.5^{21}}{(5^{2})^{10}}:\frac{5.(3.7.7^{14}-19.7^{14})}{7.7^{15}+3.7^{15}}[/tex]
=[tex]\frac{5^{21}}{5^{20}}:\frac{5.7^{14}.2}{7^{15}.10}=5.\frac{7^{14}}{7^{15}}=5.\frac{1}{7}=\frac{5}{7}[/tex]
Câu a sai rồi nha haizz
[tex]\frac{2.5.5^{21}-9.5^{21}}{(5^{2})^{10}}:\frac{5.(3.7.7^{14}-19.7^{14})}{7.7^{15}+3.7^{15}}[/tex]
=[tex]\frac{5^{21}}{5^{20}}:\frac{5.7^{14}.2}{7^{15}.10}=5.\frac{7^{14}}{7^{15}}=5.\frac{1}{7}=\frac{5}{7}[/tex]