Ta có: \(\left(2+4+6+...+2004\right)\cdot x=501396\)
\(\Leftrightarrow\frac{\left(2+2004\right)\cdot\left[\left(2004-2\right)\div2+1\right]}{2}\cdot x=501396\)
\(\Leftrightarrow\frac{2006\cdot1002}{2}\cdot x=501396\)
\(\Leftrightarrow1005006\cdot x=501396\)
\(\Rightarrow x=\frac{250698}{502503}\)