Question

Tìm x thuộc Z

(x-3)+(x-2)+(x-1)+...+10+11=11

Answer 1

\(\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+...+10+11=11\)

\(\Rightarrow\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+1+...+10=0\)

\(\Rightarrow\left[\left(x-3\right)+\left(x-2\right)+\left(x-1\right)\right]+\left[1+2+3+...+10\right]=0\)

\(\Rightarrow\left(x-3\right)+\left(x-2\right)+\left(x-1\right)+55=0\)

\(\Rightarrow\left(x-3\right)+\left(x-2\right)+\left(x-1\right)=-55\)

P/s: Tự giải nốt nha!