<math xmlns="http://www.w3.org/1998/Math/MathML" id="p1.1.m1.1" class="ltx_Math" alttext="{\displaystyle X^{\prime\prime}}" display="inline">
  <semantics id="p1.1.m1.1a">
    <msup id="p1.1.m1.1.3" xref="p1.1.m1.1.3.cmml">
      <mi id="p1.1.m1.1.1" xref="p1.1.m1.1.1.cmml">X</mi>
      <mo id="p1.1.m1.1.2.1" xref="p1.1.m1.1.2.1.cmml">′′</mo>
    </msup>
    <annotation-xml encoding="MathML-Content" id="p1.1.m1.1b">
      <apply id="p1.1.m1.1.3.cmml" xref="p1.1.m1.1.3">
        <csymbol cd="ambiguous" id="p1.1.m1.1.3.1.cmml" xref="p1.1.m1.1.3">superscript</csymbol>
        <ci id="p1.1.m1.1.1.cmml" xref="p1.1.m1.1.1">𝑋</ci>
        <ci id="p1.1.m1.1.2.1.cmml" xref="p1.1.m1.1.2.1">′′</ci>
      </apply>
    </annotation-xml>
    <annotation encoding="application/x-tex" id="p1.1.m1.1c">{\displaystyle X^{\prime\prime}}</annotation>
  </semantics>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML" display="block" alttext="{\displaystyle X''}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <msup>
          <mi>X</mi>
          <mo>&#x2033;</mo>
        </msup>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle X''}</annotation>
  </semantics>
</math>