Question

\(2x^2+3x+1=0\)

\(\left(x^2+1\right)\left(x-1\right)=0\)

Answer 1

2x² + 3x + 1 = 0

\(\Rightarrow\) 2x² + 2x + x + 1 = 0

\(\Rightarrow\) 2x ( x + 1 ) + ( x + 1 ) = 0

\(\Rightarrow\) ( x + 1 )( 2x + 1 ) = 0

\(\Rightarrow\left[{}\begin{matrix}x+1=0\\2x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-1\\x=-\frac{1}{2}\end{matrix}\right.\)

\(\Rightarrow\) \(S=\left\{-1;-\frac{1}{2}\right\}\)

( x² + 1 )( x - 1 ) = 0

Mà x² + 1 > 0

=> x - 1 = 0

=> x = 1