( x +1 ) + ( x + 2 )+.....+ ( x + 2019 ) = 2049285
⇔ 2019x+ ( 1+2+3+...+2019)=2049285
⇔ 2019x + $\frac{2019(1+2019)}{2}$ =2049285
⇔ 2019( x+ $\frac{2020}{2}$ )= 2049285
⇔ x+ 1010 = 2049285 : 2019
⇔ x+ 1010=1015
⇔ x= 1015-1010
⇔ x=5
Vậy x=5
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