November 2008 SAT Subject Test: Math Level 2

<p>Oh yeah, with the graph, I got g(x) = |f(-x)|</p>

<p>I found the maximum at x=2.39 as well. </p>

<p>I'm probably wrong.</p>

<p>ZorroX99, 2,2 for equi triangle was wrong. It was -1, rt 3 or something</p>

<p>@ rjacob: was that even an option?</p>

<p>i dont think so...i think it was -2...the value was like 100+ and kept goin up from there</p>

<p>The period for |cos x| was 1pi I believe.</p>

<p>Yea, the trick answer was the hump on the graph that was like Y= 4 but f(2) = 30 was the real answer</p>

<p>It wasn't the period of |cos x| but |sin x| = 2 pi</p>

<p>yea something like that</p>

<p>"Wasn't the answer for the maximum at x=2.39?"</p>

<p>The endpoints are included, the maximum is at (-2, 4). (If its the question I think your talking about)</p>

<p>crap. I thought the hump was the maximum</p>

<p>|sin x| would still be 1pi wouldn't it?</p>

<p>Yea, I think it was |sinx|, but anyway, I got pi.</p>

<p>thats what i put</p>

<p>It asked for period of lsinxl. Period for cosx would be the same.</p>

<p>Why is it pi instead of 2 pi?</p>

<p>also, what about the one one where f(f(x))=x...which x makes it true?</p>

<p>^^^it was f(x)=-x</p>

<p>and the period to the function of Absolute value sinx was only pi</p>

<p>The answer for that maximum problem was 0.28</p>

<p>It was -x^3 + something something</p>

<p>Any value greater than one returned a negative result, and all the negative choices also returned a negative result, as they were too large. 0.28 returned a postive result, I plugged every choice in and all the rest were negative.</p>

<p>No, since it's absolute value it would bounce off the graph (which would represent the -y value curve w/o abs value). That was the supposed trick. You were supposed to use the formula to find the period 2pi/a. Since a = 1 (|1 sin x|) it was 2pi</p>

<p>Because the graph shows humps instead of a wave form. And the humps repeat every pi. Period = how long it takes for the trig function to make a full cycle (repeat itself).</p>

<p>Without the absolute value it would be equal to 2pi.</p>

<p>another question was ln (something) = (something)</p>

<p>easy, put in e^x for left hand side.</p>

<p>f(f(x))=x...which x makes it true?</p>

<p>Think of the absolute value of either sin or cosine of x as full wave rectified AC voltage (ok so not many of you guys deal with electric stuff but heres a graphic... Image:Rectified</a> waves.png - Wikipedia, the free encyclopedia</p>

<p>As a result, the period is decreased to pi, as the function never goes negative, instead repeating its positive half over and over with a period of pi.</p>