[tex]Bài 1:Cho biểu thức A= 2012/(0,(2012))+ 2012/(0,0(2012))+ 2012/(0,00(2012)). Hãy phân tích A thành thừa số nguyên tố[/tex]
[tex]A=\frac{2012}{(0,(2012))}+\frac{2012}{(0,0(2012))}+\frac{2012}{0,00(2012)} \\=2012.\frac{1}{(0,(2012))}+2012.\frac{1}{(0,0(2012))}+2012.\frac{1}{(0,00(2012))}\\=2012.(\frac{1}{\frac{2012}{9999}}+\frac{1}{\frac{2012}{99990}}+\frac{1}{\frac{2012}{999900}})\\=2012.(\frac{9999}{2012}+\frac{99990}{2012}+\frac{999900}{2012})\\=2012.\frac{1109899}{2012}\\=1109899[/tex]
[tex]1109899=3^3.11.37.101[/tex]
Vậy [tex]A=3^3*11*37*101[/tex]