Question

x+(x+1)+(x+2)+....+2018+2019=2019

Answer 1

x + ( x + 1 ) + ( x + 2 ) + ... + 2018 + 2019 = 2019

x + ( x + 1 ) + ( x + 2 ) + ... + 2018 = 0 ( giảm cả hai vế cho 2019 )

 Ta có \(\frac{\left(x+2018\right)\times n}{2}=0\)     ( n là số số hạng )

\(\Rightarrow\left(x+2018\right)\times n=0\div2\)

\(\Rightarrow\left(x+2018\right)\times n=0\)

\(\Rightarrow x+2018=n\div2\) 

\(\Rightarrow x+2018=0\)

\(\Rightarrow x=0-2018\)

\(\Rightarrow x=-2018\)