Đáp án:
`A>B`.
Giải thích các bước giải:
`A=(10^2004+1)/(10^2005+1`
`=>10A=(10.(10^2004+1))/(10^2005+1`
`=>10A=(10^2005+10)/(10^2005+1`
`=>10A=(10^2005+1+9)/(10^2005+1`
`=>10A=(10^2005+1)/(10^2005+1)+9/(10^2005+1`
`=>10A=1+9/(10^2005+1`
`B=(10^2005+1)/(10^2006+1`
`=>10B=(10.(10^2005+1))/(10^2006+1`
`=>10B=(10^2006+10)/(10^2006+1`
`=>10B=(10^2006+1+9)/(10^2006+1`
`=>10B=(10^2006+1)/(10^2006+1)+9/(10^2006+1)`
`=>10B=1+9/(10^2006+1`
`=>9/(10^2005+1)>9/(10^2006+1)`
`=>1+9/(10^2005+1)>1+9/(10^2005+1`
`=>10A>10B`
`=>A>B`
Vậy `A>B`.