`a) (2x + 5)^2 - (x + 2)^2 = 0`
`=> (2x + 5 + x + 2)(2x + 5 - x - 2) = 0`
`=> (3x + 7)(x + 3) = 0`
`=>` \(\left[ \begin{array}{l}3x + 7 = 0\\x + 3 = 0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}3x = -7 => x = \dfrac{-7}{3}\\x = -3\end{array} \right.\)
`b) (x + 1)(7x + 2) - 2x^2 - 4x - 2 = 0`
`=> 7x^2 + 2x + 7x + 2 - 2x^2 - 4x - 2 = 0`
`=> (7x^2 - 2x^2) + (2x - 4x + 7x) (2 - 2) = 0`
`=> 5x^2 + 5x = 0`
`=> x(5x + 5) = 0`
`=> \(\left[ \begin{array}{l}x = 0\\5x + 5 = 0 => 5x = -5 => x = -1\end{array} \right.\)
