a) $2(x+5)-x²-5x=0$
$⇔2x+10-x²-5x=0$
$⇔2(x+5)-x(x+5)=0$
$⇔(x+5)(2-x)=0$
$⇔$ \(\left[ \begin{array}{l}x+5=0\\2-x=0\end{array} \right.\)
$⇔$ \(\left[ \begin{array}{l}x=-5\\x=2\end{array} \right.\)
b) $2x²+3x-5=0$
$⇔2x²-2x+5x-5=0$
$⇔2x(x-1)+5(x-1)=0$
$⇔(x-1)(2x+5)=0$
$⇔$ \(\left[ \begin{array}{l}x-1=0\\2x+5=0\end{array} \right.\)
$⇔$ \(\left[ \begin{array}{l}x=1\\x=-5/2\end{array} \right.\)