Đáp án:
$\begin{array}{l}
1)\,\,\,\,\\
{(x + 4)^2} - (x + 1)(x - 1) = 16\\
{x^2} + 8x + 16 - ({x^2} - 1) - 16 = 0\\
{x^2} + 8x + 16 - {x^2} + 1 - 16 = 0\\
8x + 1 = 0\\
x = \frac{{ - 1}}{8}\\
2)\,\,\,\\
{(2x - 1)^2} + {(x + 3)^2} - 5(7 + x)(x - 7) = 0\\
4{x^2} - 4x + 1 + {x^2} + 6x + 9\, - 5.(x + 7)(x - 7) = 0\\
5{x^2} + 2x + 10 - 5.({x^2} - 49) = 0\\
5{x^2} + 2x + 10 - 5{x^2} + 245 = 0\\
2x + 255 = 0\\
2x = - 255\\
x = \frac{{ - 255}}{2}
\end{array}$
