$a)$ $0,(46)$ $=$ $0,46464646...$
$0,4(64)$ $=$ $0,46464646...$
Vậy $0,(46)$ $=$ $0,4(64)$
$b)$ Cách $1$ $:$ $ 1,(454)$ $=$ $0,(001)$ $.$ $454$ $+$ $1$ $=$ $\dfrac{1}{999}$ $.$ $454$ $+$ $1$ $=$ $\dfrac{454}{999}$ $+$ $1$ $=$ $\dfrac{1453}{999}$
$1,4(545)$ $=$ $0,0(001)$ $.$ $545$ $+$ $1,4$ $=$ $\dfrac{1}{9990}$ $.$ $545$ $+$ $1,4$ $=$ $\dfrac{109}{1998}$ $+$ $1,4$ $=$ $\dfrac{14531}{9990}$
Vì $\dfrac{1453}{999}$ $<$ $\dfrac{14531}{9990}$
Suy ra $:$ $1,(454)$ $<$ $1,4(545)$
Cách $2$ $:$ $1,(454)$ $=$ $1,454454454...$
$1,4(545)$ $=$ $1,4545545545...$
Vì $1,454454454...$ $<$ $1,4545545545...$
Vậy $1,(454)$ $<$ $1,4(545)$
Cách 2 mình làm cho bạn tham khảo thôi nha, theo mình cách 1 vẫn tốt hơn $!$
HỌC TỐT NHÉ!!
