$(2x - 1)(2x + 1) - 4(x + 5)^2 = 19$
$4x^2 - 1 - 4(x^2 + 10x + 25) = 19$
$4x^2 - 1 - 4x^2 - 40x - 100 = 19$
−40x = 19 + 1 + 100
−40x = 120
x = −3