F4.ptx

<exercise>
  <statement>
    <p>
      Determine which of the following ODEs is exact.
    </p>
    <xsl:for-each select="odes/*">
      <me><xsl:value-of select="."/></me>
    </xsl:for-each>
    <p>
      Then find an implicit solution for this exact ODE
      satisfying the initial value
      <m>y(<xsl:value-of select="t0"/>)=<xsl:value-of select="y0"/></m>.
    </p>
  </statement>
  <answer>
    <p>The following ODE is exact.</p>
    <me><xsl:value-of select="exact_ode"/></me>
    <p>
      Its implicit solution satisfying the initial value is:
    </p>
    <me><xsl:value-of select="solution"/></me>
  </answer>
</exercise>