$a.2x^2 + 5x - 3 = 0$
$⇔(2x^2 - x) + (6x - 3) = 0$
$⇔x(2x - 1) + 3(2x - 1) = 0$
$⇔(x + 3)(2x - 1) = 0$
⇔\(\left[ \begin{array}{l}x+3=0\\2x-1=0\end{array} \right.\)⇔ \(\left[ \begin{array}{l}x=-3\\x=\frac{1}{2}\end{array} \right.\)
$b.2x^2 + 5x + 3 = 0$
$⇔(2x^2 + 2x) + (3x + 3) = 0$
$⇔2x(x + 1) + 3(x + 1) = 0$
$⇔(2x + 3)(x + 1) = 0$
⇔\(\left[ \begin{array}{l}2x+3=0\\x+1=0\end{array} \right.\) ⇔ \(\left[ \begin{array}{l}x=\frac{-3}{2}\\x=-1\end{array} \right.\)
