`A=|x-1004|-|x+1003|`
`A=(-x +1004) - (-x-1003)=1004+1003`
`A=(-x+1004)-(-x-1003)=2007`
Ta có:
`x≥-1003`
`⇒x+(-1003)≥0`
`x` < `1004`
`⇒x-1004` < `0`
Ta lại có:
$\begin{cases}x-1004≥0⇒|x-1004|=x-1004\\x+1003≥0⇒|x+1003|=x+1003\\\end{cases}$
Vậy `MAX_A` `=` `2007` `⇔` `x` < `-1003`