<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
   <semantics xmlns="">
      <mrow>
         <mi>S</mi>
         <mo stretchy="false">(</mo>
         <mi>x</mi>
         <mo stretchy="false">)</mo>
         <mo>=</mo>
         <mn>3</mn>
         <mi>x</mi>
         <mo>+</mo>
         <mn>1</mn>
      </mrow>
      <annotation encoding="application/x-tex">S(x)=3x+1</annotation>
   </semantics>
</math>
