MathML and SVG embedded in XHTML

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