Bài làm
( X + 1 ) + ( X + 2 ) + ( X + 3 ) ... + ( X + 2018 ) = 2037171
( X + X + X + ......+ X ) + ( 1 + 2 + 3 + ....+ 2018 ) = 2037171
2018 x X + ( 2018 + 1 ) x 2018 : 2 = 2037171
2018 x X + 2037171 = 2037171
2018 x X = 2037171 - 2037171
2018 x X = 0
X = 0 : 2018
X = 0