description(s)
<h5>
y=<span id="fval">f</span>
<input type="text" id="fv" name="fname" value="cube(x)" onblur="toggle()" />
for <span id="maval">a <=x<= a</span>
<input type="button" value="-" onclick="a-=.25;update()"/>
<input type="button" value="+" onclick="a+=.25;update()"/>
</h5>
</center>
</body>
