<exercise>
<statement>
<p>
Modify the line of SageMath code
<c>t,y = var('t y'); plot_slope_field(FIXME, (t,-5,5), (y,-5,5))</c>
and run it at <url href="https://sagecell.sagemath.org/"/> to
produce the direction field for the ODE <m><xsl:value-of select="ode"/></m>.
</p>
<p>
Then explain how to use its direction field to approximate the
value of <m>y(<xsl:value-of select="othert"/>)</m> given
the initial value <m>y(<xsl:value-of select="t0"/>)=<xsl:value-of select="y0"/></m>.
</p>
</statement>
<answer>
<p>
Replace <c>FIXME</c> with <c><xsl:value-of select="field_sage"/></c> to show
the direction field. Then sketch a curve passing through the initial value
to show that
<m>y(<xsl:value-of select="othert"/>)\approx<xsl:value-of select="othery"/></m>.
</p>
</answer>
</exercise>
