từ \(x_1\)+ \(x_2\) +........+ \(x_{2007}\)= 0
==>( x1 + x2) + ( x3+x4) +.......+ ( x2005 + x2006) + x2007= 0
==> 1+ 1 +.....+ 1 + x1007 = 0 ( 1003 số 1)
=> 1003 + x2007 = 0
=> x2007 = 0 - 1003
=> x2007 = -1003
vì x2007 + x1= 1 ==> -1003+ x1=1==> x1 = 1- 1003= -1002
Vậy x1 = -1002 ( tick nha)