<p>how do you get from </p>
<p>(a^2 - b^2)/[(1/a)-(1/b)]</p>
<p>to</p>
<p>-ab(a+b)</p>
<p>it's probably easy but i cant seem to get it. i think i have some rule mixed up or something.</p>
<ol>
<li>factor the numerator to: (a+b)(a-b)</li>
<li>put the denom. into LCD form: (b-a)/ab</li>
<li>Bring out a neg sign for the numerator so it becomes: -(a+b)(b-a)</li>
<li>now the expression looks like: -(a+b)(b-a)/[(b-a)/(ab)],
so simplify & cancel out (b-a) terms, & do fractional math so that term (ab) is multiplied with the current numerator & remaining terms become:
-ab(a+b)</li>
</ol>
<p>thanks!4354354354354354353434543w</p>