Question

Tìm x biết: 10 + 11 + 12 + 13+ ...  + x = 5106.

Answer 1

\(\frac{\left(x+10\right)\left[\left(x-10\right)+1\right]}{2}=5106\)

\(\Rightarrow\left(x+10\right)\left(x-9\right)=5106.2=10212\)

Vậy.................