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<p>Oops; I forgot to explain that! Sorry!</p>
<p>A CAS is a Computer Algebra System. The most common calculator that has a CAS is probably the TI-89 Titatnium. It does what it sounds like it does: it can do symbolic manipulation. For example, it can differentiate and integrate equations, something that a TI-83 and TI-84 can’t do. Consequentially, many AP Calculus teachers ban the TI-89 in their classes (though the AP exam doesn’t do the same).</p>
<p>Using my above example (solve e^(4x)=37581 for x), the TI-89’s CAS would use this input:</p>
<p>solve(e^(4x)=37581,x)</p>
<p>And spit out the value of x.</p>
<p>However, there’s no need to spend $130 on a new graphing calculator. A TI-83 or 84 (which is what I assume your son has) is definitely enough for the Math II exam. As I mentioned earlier, knowing when using a calculator can save time and improve accuracy is crucial to success on the Math Subject Tests (though not so much on the SAT Math section).</p>