`( x + 1 ) + ( x + 2 ) + ( x + 3 ) + .... + ( x + 100 ) = 0`
`⇔ ( x + x + ... + x ) + ( 1 + 2 + 3 + ... + 100 ) = 0`
`⇔ x . 100 + ( 100 + 1 ) . 100 : 2 = 0`
`⇔ x . 100 + 101 . 100 : 2 = 0`
`⇔ x . 100 + 10100 : 2 = 0`
`⇔ x . 100 + 5050 = 0`
`⇔ x . 100 = 0 - 5050`
`⇔ x . 100 = - 5050`
`⇔ x = -5050 : 100`
`⇔ x = -50,5`
Vậy , `x = -50,5`