The mfrac element is used to display a fraction.
<math> <mfrac> <mi>y</mi> <mn>3</mn> </mfrac> </math>
If the fraction contains a single element in the numerator and a single element in the denominator, then the simple coding show above will work.
<math> <mfrac> <mrow> <mn>3</mn> <mi>y</mi> </mrow> <mrow> <mn>12</mn> </mrow> </mfrac> </math>
If either the numerator or the denominator, or both, contain multiple elements, then use the mrow element to specify which elements go in the numerator and which go in the denominator.
<math> <mfrac> <mrow> <mn>2</mn> <mi>x</mi> <mo>-</mo> <mn>14</mn> <mo>+</mo> <mn>3</mn> <mo>(</mo> <mi>x</mi> <mo>+</mo> <mn>2</mn> <mo>)</mo> </mrow> <mrow> <mn>6</mn> <mo>(</mo> <mn>2</mn> <mi>x</mi> <mo>+</mo> <mn>2</mn> <mo>-</mo> <mn>4</mn> <mo>(</mo> <mn>4</mn> <mi>x</mi> <mo>-</mo> <mn>2</mn> <mo>)</mo> <mo>)</mo> </mrow> </mfrac> </math>
Using the row element and the mo element to define parentheses, you can define some pretty complex fractional expressions, as shown above.
<math> <mfrac> <mfrac bevelled="true"> <mi>y</mi> <mn>3</mn> </mfrac> <mn>12</mn> </mfrac> </math>
By nesting mfrac elements you can create multi-level fractions. A multi-level fraction can sometimes be made more understandable by using a diagonal fraction bar. To create a diagonal fraction bar, add the bevelled attribute, set to "true", to the mfrac opening tag.
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