Ta có 1212/1313= 12/13
=> 1212/1313 =12/13
\(\frac{12}{13}=\frac{12.101}{13.101}=\frac{1212}{1313}\)
\(\Rightarrow\frac{12}{13}=\frac{1212}{1313}\)
\(\frac{12}{13}=\frac{12\cdot101}{13\cdot101}=\frac{1212}{1313}\)
\(\Rightarrow\frac{12}{13}=\frac{1212}{1313}\)