<p>l'hopital's rule</p>

<p>if you're like me and never learned the lim(x-->0) sin(x)/x and the cos one and the e^ one, just learn this easy rule</p>

<p>lim(x-->b) f(x)/g(x) = lim(x-->b) f'(x)/g'(x)</p>

<p>so in the sin(x)/x problem, take the derivative of sin(x) and x, and you get cos(x)/1. substituting 0 gives you 1. saved me some memorization</p>