power3

- ( (x + y) ^ (n - 3) )

W3C sample	WIRIS
	$-(x+y)^{(n-3)}$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <minus/>
    <apply>
      <power/>
      <apply>
        <plus/>
        <ci>x</ci>
        <ci>y</ci>
      </apply>
      <apply>
        <minus/>
        <cn>n</cn>
        <cn>3</cn>
      </apply>
    </apply>
  </apply>
</math>

Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)