Vì $\frac{7^{2010}+1}{7^{2011}-1}$ < 1=>$\frac{7^{2010}+1}{7^{2011}-1}$<$\frac{7^{2010}+7+1}{7^{2011}+7-1}$=>$\frac{7^{2010}+1}{7^{2011}-1}$ <$\frac{7^{2010}+7^{1}+1}{7^{2011}+7^{1}-1}$=>$\frac{7^{2010}+1}{7^{2011}-1}$<$\frac{7^{2011}+1}{7^{2012}-1}$
