=> 50x + (99 + 1).50:2 = 0
50x + 2500 = 0
50x = -2500
x = -50
(x+1)+(x+3)+...+(x+99)=0
x+1+x+2+...+x+99=0
50x + (99+1)x50:2=0
50x+2500=0
50x=0-2500=-2500
x=-2500:50
x=-50
(x+1)+(x+3)+.........+(x+99)=0
=>(x+x+....50 số x......+x)+(1+3+5+.......+99)=0
=>50x+2500=0
=>50x=-2500
=>x=-50