a) x( x + 5 ) - ( x + 2 )² = 0
⇔ x² +5x - x² - 4x - 4 = 0
⇔ x = 4
b) 2x( x - 3 ) - 3( x - 3 ) = 0
⇔ ( 2x - 3 )( x - 3 ) = 0
⇔ \(\left[ \begin{array}{l}2x-3=0\\x-3=0\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x=\frac{3}{2}\\x=3\end{array} \right.\)