<math xmlns="http://www.w3.org/1998/Math/MathML">
  <semantics>
    <mrow>
      <msup>
        <mi>f</mi>
        <mn>-1</mn>
      </msup>
      <mo>&ApplyFunction;</mo>
      <mfenced close=")" open="(">
        <mi>x</mi>
      </mfenced>
    </mrow>
    <annotation-xml encoding="MathML-Content">
      <apply>
        <apply>
          <inverse/>
          <ci type="function">f</ci>
        </apply>
        <ci>x</ci>
      </apply>
    </annotation-xml>
    <annotation encoding="SnuggleTeX">$f^{-1}(x)$</annotation>
    <annotation encoding="LaTeX">$f^{-1}(x)$</annotation>
    <annotation encoding="Maxima">inverse[f](x)</annotation>
  </semantics>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <semantics>
    <mrow>
      <msup>
        <mi>f</mi>
        <mn>-1</mn>
      </msup>
      <mfenced close=")" open="(">
        <mi>x</mi>
      </mfenced>
    </mrow>
    <annotation encoding="SnuggleTeX">$f^{-1}(x)$</annotation>
  </semantics>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
    <msup>
      <mi>f</mi>
      <mn>-1</mn>
    </msup>
    <mo>&ApplyFunction;</mo>
    <mfenced close=")" open="(">
      <mi>x</mi>
    </mfenced>
  </mrow>
</math>

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <apply>
      <inverse/>
      <ci type="function">f</ci>
    </apply>
    <ci>x</ci>
  </apply>
</math>

inverse[f](x)