\(B=\frac{1}{2019}+\frac{2}{2019}+\frac{3}{2019}+...+\frac{2019}{2019}\)
\(=\frac{1+2+3+...+2019}{2019}\)
\(=\frac{\left(2019+1\right).\left[\left(2019-1\right)+1\right]:2}{2019}\)
\(=\frac{2039190}{2019}\)
\(=1010\)
#)Giải :
\(B=\frac{1}{2019}+\frac{2}{2019}+\frac{3}{2019}+...+\frac{2019}{2019}\)
\(B=\frac{1+2+3+...+2018+2019}{2019}\)
\(B=\frac{\frac{\left(2019+1\right)\times2019}{2}}{2019}\)
\(B=\frac{2039190}{2019}\)
\(B=\frac{1}{2019}+\frac{2}{2019}+\frac{3}{2019}+\frac{4}{2019}+...+\frac{2019}{2019}\)
\(B=\frac{1+2+3+4+...+2019}{2019}\)
\(B=\frac{\frac{\left(2019+1\right)\times2019}{2}}{2019}\)
\(B=\frac{2039190}{2019}\)
\(B=1010\)
\(B= 2019 1 + 2019 2 + 2019 3 +...+ 2019 2019 B=\frac{1+2+3+...+2018+2019}{2019}B= 2019 1+2+3+...+2018+2019 B=\frac{\frac{\left(2019+1\right)\times2019}{2}}{2019}B= 2019 2 (2019+1)×2019 B=\frac{2039190}{2019}B= 2019 2039190 \)
#YTB
\(B=\frac{1}{2019}+\frac{2}{2019}+...+\frac{2019}{2019}\)
\(=\frac{1+2+...+2019}{2019}\)
\(=\frac{\left(2019+1\right)\times\left[\left(2019-1\right)\div1+1\right]\div2}{2019}\)
\(=\frac{2020\times2019\div2}{2019}\)
\(=\frac{1010.2019}{2019}=1010\)