Move right part of the equation to
left part with negative sign.
The equation is transformed from
$$\left(x - 17\right)^{2} + \left(y + 26\right)^{2} = 2 \cdot 16 \left(x - 17\right) + 2 \left(y + 26\right)$$
to
$$\left(- 2 \cdot 16 \left(x - 17\right) - 2 \left(y + 26\right)\right) + \left(\left(x - 17\right)^{2} + \left(y + 26\right)^{2}\right) = 0$$
Expand the expression in the equation
$$\left(- 2 \cdot 16 \left(x - 17\right) - 2 \left(y + 26\right)\right) + \left(\left(x - 17\right)^{2} + \left(y + 26\right)^{2}\right) = 0$$
We get the quadratic equation
$$x^{2} - 66 x + y^{2} + 50 y + 1457 = 0$$
This equation is of the form
a*x^2 + b*x + c = 0
A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$x_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$x_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 1$$
$$b = -66$$
$$c = y^{2} + 50 y + 1457$$
, then
D = b^2 - 4 * a * c =
(-66)^2 - 4 * (1) * (1457 + y^2 + 50*y) = -1472 - 200*y - 4*y^2
The equation has two roots.
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
or
$$x_{1} = \frac{\sqrt{- 4 y^{2} - 200 y - 1472}}{2} + 33$$
$$x_{2} = 33 - \frac{\sqrt{- 4 y^{2} - 200 y - 1472}}{2}$$