data/mathtoweb/181.mml
<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>U</mi><mn>4</mn></msub><mrow><mo rspace="0.3em" lspace="0em" stretchy="true" fence="true" form="prefix">(</mo><mi>x</mi><mo rspace="0em" lspace="0.3em" stretchy="true" fence="true" form="postfix">)</mo></mrow><mo>=</mo><mn>16</mn><msup><mi>x</mi><mn>4</mn></msup><mo>-</mo><mn>12</mn><msup><mi>x</mi><mn>2</mn></msup><mo>+</mo><mn>1</mn></mrow></math>