K's Avalon!

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MathML example

Given the quadratic equation $a<!--\; \; -->x^2+b<!--\; \; -->x+c=\; 0$ , the roots are given by $x=\frac{-<!--\; -\; -->b\pm <!--\; \pm \; -->\sqrt{b^2-<!--\; -\; -->4<!--\; \; -->a<!--\; \; -->c}}{2<!--\; \; -->a}$ .