$(x - 8)^2 - x(x + 6) = -2$
$x^2 - 16x + 64 - x^2 - 6x = -2$
−16x − 6x = −2 − 64
−22x = −66
x = −66 : −22
x = 3

$(x + 7)^2 = (x - 3)(x + 3)$
$x^2 + 14x + 49 = x^2 - 9$
$x^2 - x^2 + 14x = -49 - 9$
14x = −58
$x = -\frac{58}{14} = -\frac{29}{7} = -4\frac{1}{7}$

$(2x + 1)^2 - (2x - 1)(2x + 3) = 0$
$4x^2 + 4x + 1 - (4x^2 - 2x + 6x - 3) = 0$
$4x^2 + 4x + 1 - 4x^2 + 2x - 6x + 3 = 0$
4x + 2x − 6x = −1 − 3
0x = −4
0 ≠ −4, уравнение не имеет корней.

$x(x - 2) - (x + 5)^2 = 35$
$x^2 - 2x - (x^2 + 10x + 25) = 35$
$x^2 - 2x - x^2 - 10x - 25 = 35$
−2x − 10x = 35 + 25
−12x = 60
x = 60 : (−12)
x = −5