Question

(x+1)+(x+2)+(x+3)+...+(x+100)=8080

Answer 1

x+(x+1)+(x+2)+...(x+100)=8080

(x+x+x+..+x)+(0+1+2+...+100)=8080

101x+5050=8080

101x=8080-5050

101x=3030

x=3030:101

x=30

Answer 2

`(x+1)+(x+2)+...+(x+100) = 8080`       [có `100` nhóm]

`=> (x+x+...+x) + (1+2+...+100) = 8080     `

`=> 100x + (100+1).[(100-1):1 + 1] : 2 = 8080`

`=> 100x + 5050 = 8080`

`=> 100x = 3030`

`=> x = 30,3`

Vậy `x = 30,3`