Question

Tìm \(x\) 

 (\(x\) + 1) + (\(x\) + 4) + (\(x\) + 7 ) + (\(x\) + 10 ) + ... + (\(x\) + 28 ) = 156

Answer 1

Tách riêng thánh hai nhóm (x+x+x+...+x)+(1+4+7+10+...+28)=10x+145=156. Vậy x=11/10

Answer 2

\(\left(x+1\right)+\left(x+4\right)+...........+\left(x+28\right)=156\)

\(\Rightarrow x+1+x+4+..........+x+28=156\)

\(\Rightarrow10x+\left(1+4+.........+28\right)=156\)

\(\Rightarrow10x+145=156\)

\(\Rightarrow10x=11\)

\(\Rightarrow x=1,1\)

Answer 3

x = 1,1 nha bạn