Solve LaTeX: \displaystyle x^{2} - 16 x + 128 = 0

Using the quadratic formula gives LaTeX: \displaystyle x=\frac{ -(-16)\pm \sqrt{ (-16)^2 -4(1)(128) } }{ 2(1) }
Simplifying gives LaTeX: \displaystyle x=\frac{ 16 \pm \sqrt{ -256 } }{ 2 } = 8 \pm -8 i