a)\(x^2+x+2016=0\)
\(\Rightarrow x^2+x+\frac{1}{4}+\frac{8063}{4}=0\)
\(\Rightarrow\left(x+\frac{1}{2}\right)^2+\frac{8063}{4}>0\forall x\)
Suy ra vô nghiệm
b)\(x-2\left(x+1\right)=0\)
\(\Rightarrow x-2x-2=0\)
\(\Rightarrow-x-2=0\)
\(\Rightarrow x=-2\)