Lời giải:
a)
\(\frac{64}{73}=1-\frac{9}{73}=1-\frac{18}{146}\); \(\frac{45}{51}=1-\frac{6}{51}=1-\frac{18}{153}\)
Mà \(\frac{18}{146}> \frac{18}{153}\Rightarrow 1-\frac{18}{146}< 1-\frac{18}{153}\)
\(\Rightarrow \frac{64}{73}<\frac{45}{51}\)
b)
\(\frac{2323}{2424}=\frac{2300+23}{2400+24}=\frac{23(100+1)}{24(100+1)}=\frac{23}{24}=1-\frac{1}{24}\)
\(\frac{20132013}{20142014}=\frac{20130000+2013}{20140000+2014}=\frac{2013(10000+1)}{2014(10000+1)}=\frac{2013}{2014}=1-\frac{1}{2014}\)
Mà \(\frac{1}{24}>\frac{1}{2014}\Rightarrow 1-\frac{1}{24}< 1-\frac{1}{2014}\Rightarrow \frac{2323}{2424}< \frac{20132013}{20142014}\)