\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+2019\right)+2019=2019\\ =>\left(x+x+x+...+x\right)+\left(1+2+...+2019\right)=0\\ =>2020x+\dfrac{\left(2019+1\right).2019}{2}=0\\ =>2020x+\dfrac{2020.2019}{2}=0\\ =>2020.\left(x+\dfrac{2019}{2}\right)=0\\ =>x+\dfrac{2019}{2}=0\\ =>x=-\dfrac{2019}{2}\left(KTM\right)\)
\(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+2019\right)+2019=2019\)
\(\Rightarrow2020x+\left[\left(2019+1\right).2019:2\right]=0\)
\(\Rightarrow2020x+2020.2019:2=0\)
\(\Rightarrow2020x+2039190=0\)
\(\Rightarrow x=\dfrac{2019}{2}\)