a) $-5x+3x^2=0⇔ x(-5+3x)=0$
⇔\(\left[ \begin{array}{l}x=0\\-5+3x=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=0\\x=5/3\end{array} \right.\)
b) $pt⇔5x^2-10x=5x^2+3x-5x-3$⇔$10x+3x-5x=3$⇔$8x=3⇔x=3/8$
c) $pt⇔16x^2+24x+9=4x^2-8x+4$⇔$12x^2+32x+5=0⇔$\(\left[ \begin{array}{l}x=-1/6\\x=-5/2\end{array} \right.\)