<?xml version="1.0"?>
<!-- ====================================================================== -->
<!-- File: quadratic_formula_presentation.mml                               -->
<!-- Author: Pankaj Kamthan                                                 -->
<!-- Date: Oct 20, 1998                                                     -->
<!-- Description: Quadratic formula in MathML Presentation Markup.          -->
<!-- ====================================================================== -->

<math>
<mrow>
  <mi>x</mi>
  <mo>=</mo>
  <mfrac>
    <mrow>
      <mrow>
        <mo>-</mo>
        <mi>b</mi>
      </mrow>
      <mo>&PlusMinus;</mo>
      <msqrt>
        <mrow>
          <msup>
            <mi>b</mi>
            <mn>2</mn>
          </msup>
          <mo>-</mo>
          <mrow>
            <mn>4</mn>         
            <mo>&InvisibleTimes;</mo>
            <mi>a</mi>        
            <mo>&InvisibleTimes;</mo>
            <mi>c</mi>
          </mrow>
        </mrow>
      </msqrt>
    </mrow>
    <mrow>
      <mn>2</mn>
      <mo>&InvisibleTimes;</mo>
      <mi>a</mi>
    </mrow>
  </mfrac>
</mrow>
</math>