Question

Answer 1

Vì \(x^2+1>0\) mọi \(x\in R\)

\(\Rightarrow4x+2=0\Rightarrow x=-\dfrac{1}{2}\)

Answer 2

\(\left\{{}\begin{matrix}4x+2=0\\x^2+1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x=-2\\x^2=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{-1}{2}\\x=+-1\end{matrix}\right.\)

Answer 3

$\to 4x+2=0\to x=-2$