a) Ta có : \(-0,636363...=-0,\left(63\right)=\left(-\frac{63}{99}\right)=-\frac{7}{11}\)
Mà \(-7=-7\)nên \(-\frac{7}{11}=-\frac{7}{11}\)
Vậy \(-0,636363...=-\frac{7}{11}\)
b) Ta có : \(0,\left(237\right)=\frac{237}{999}\)
\(0,237=\frac{237}{1000}\)
Mà \(\frac{237}{999}>\frac{237}{1000}\)nên \(0,\left(237\right)>0,237\)
c) Ta có : \(0,\left(5\right)=\frac{5}{9}\)
\(0,\left(2\right)=\frac{2}{9}\)
=> \(0,\left(5\right)+0,\left(2\right)=\frac{5}{9}+\frac{2}{9}=\frac{7}{9}\)
\(0,5+0,2=\frac{5}{10}+\frac{2}{10}=\frac{7}{10}\)
Mà \(\frac{7}{9}>\frac{7}{10}\)nên \(0,\left(5\right)+0,\left(2\right)>0,5+0,2\)
