Solve LaTeX: \displaystyle x^{2} - 8 x + 20 = 0

Using the quadratic formula gives LaTeX: \displaystyle x=\frac{ -(-8)\pm \sqrt{ (-8)^2 -4(1)(20) } }{ 2(1) }
Simplifying gives LaTeX: \displaystyle x=\frac{ 8 \pm \sqrt{ -16 } }{ 2 } = 4 \pm 2 i