Ta có: x + (x+1)+(x+2)+...+(x+10)=154
=> (x+x+..+x) + (1+2+...+10)=154
=> 10x + 55 = 154
=> 10x = 154 - 55
=> 10x =99
=> x = 99:10
=> x=9,9
Vậy x = 9,9
x+(x+1)+(x+2)+...+(x+10)=154
x.11+(1+2+3+4+5+6+7+8+9+10)=154
x.11+ 55 = 154
x.11 =154-55
x.11 =99
x =99 : 11
x =9
x + (x +1) + (x +2) + (x +3) +... + (x+10) = 154
(X x 10) + (1+2+3+..+10) = 154
(X x 10) + (1 + 10) x 10 : 2 = 154
X x 10 + 55 = 154
X x 10 = 154 - 55
X x 10 = 99
X = 99 : 10
x = 9.9