$$4r^2+16\cdot5^{1/2}r+80 = 0$$
Answer
$$ \begin{matrix}r_1 = -4+2i & r_2 = -4-2i \\[1 em] \end{matrix} $$
Explanation
$$ \begin{aligned} 4r^2+16\cdot5^{1/2}r+80 &= 0&& \text{multiply ALL terms by } \color{blue}{ 2 }. \\[1 em]2\cdot4r^2+216\cdot5^{1/2}r+2\cdot80 &= 2\cdot0&& \text{cancel out the denominators} \\[1 em]8r^2+64r+160 &= 0&& \\[1 em] \end{aligned} $$
$ 8x^{2}+64x+160 = 0 $ is a quadratic equation.
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