<p>Test 4 Section 6</p>
<h1>7- If 18 root18 = r root t, where r and t are positive integers and r is greater than t, which of the following could be the value of rt?</h1>
<p>A. 18
B. 36
C. 108
D. 162
E. 324 </p>
<p>I got answer E because I just squared both sides of the equation and got rt=324. But, I don't understand why that is wrong. The book says the answer is C. How did they get that?</p>
<p>18 root 18 can be simplified to 54 root 2. Therefore 54 root 2 = r root t</p>
<p>It follows then that r = 54 and t=2, so rt= (54)(2) = 108</p>
<p>but what is 18 root 18 squared? Is that 324? Or am I doing the math wrong?</p>
<p>lol, you’re doing the wrong math. The question is asking for the value of rt, and r and t are given to you in the equation r root t = 18 root 18.</p>
<p>Now, given that relationship you would immediately assume that r = 18 and t=18, but that’s not the case as the questions states that r>t.</p>
<p>So when you plug in 18 root 18 in your calculator you would see that it 18 root 18 is equal to 54 root 2. this satisfies the equation r>t as 54 >2</p>
<p>So taking r= 54 and t= 2, rt= 54*2= 108</p>
<p>"/ I hope this is clear!!!</p>
<p>but I don’t understand why I cant square both sides of the equation. I know I’m probably making a silly mistake right now…but I don’t understand why I can’t square both sides.</p>
<p>Squaring both sides, you’d end up with r^2 * t. What do you do after that?</p>
<p>And (18*root18)^2 = 18^3</p>
<p>so your saying that r^2t wold not help us to solve this problem…so that’s why you have to factor the square root. Am I right?</p>
<p>See, if you have one integer and one root, you can easily equate those to r and t. You could’ve done so with 18 and root 18 except that r and t are unequal. So what you have to do is find two other numbers whose product is the product 18*root18, and one of which is a root, so that equating becomes easy.</p>
<p>You go 18^2 * 18 = r^2 * t and you end up with the same r=t, which doesn’t help. You need to factor so that the result remains the same, but the numbers change.</p>
<p>So, if I see a question like this on the real SAT, how would I know right off the bat, that I have to factor the square root, and not do what I was doing before? Would I have to try out both ways, and see which one is right, or is there a certain way that would tell me that I how I would go about doing this problem?</p>
<p>There is, actually. You never really need the calculator for the SAT I unless to save brainpower. 18^3 would be too complicated a calculation for the SAT I.</p>
<p>Also, it’s easy to see that two numbers are roots and two are not, so if you can just somehow equate them in the given conditions (r>t), you can get what you’re looking for. The simplest way is to realize that root18=root(9<em>2)=3</em>root2. So 18<em>3</em>root2=18root18 and we have a root and a proper number to equate to the values of r and t.</p>
<p>Okay, I think I understand that problem now, but I have a question in geberal about some math problems. I always have trouble with questions the have the multiple choice answers as variables. EX:
A. a + 3b - 180
B. 2a + 2b - 180
C. 180 - a -b
D. 360 - a - b
E. 360 - 2a - 3b</p>
<p>So do you have any general advice on how to solve those types of question the best? I know I’m being kind of vague, but I hope you understand what i’m trying to say. 
BTW, thanks to everyone who helped.</p>
<p>You can always plug in numbers for those. I believe this one was the horrid three triangle problem. There could’ve been no plugging in here, but I assumed another variable x as the third angle with a and b and the top triangle became b, c and 180-2x, and x was just 180-a-b…</p>
<p>They get really confusing, but always always remember that every SAT I Math problem can be solved in less than half a minute. There is a way. If you remember that, you’ll stop being intimidated, and just start feeling the traps.</p>
<p>wow, how did you know what problem I was talking about? Anyways, do you recommend any workbooks or techniques that I could use to increase my SAT score? What has helped you the most for the math section?</p>
<p>I took that test a couple of days ago and overstepped the time limit cuz of that one darned question. You don’t forget things like those. :/</p>
<p>I’ve gone through Gruber’s strategies and Grammatix, but practice is the key, along with the looking-for-shortcuts thing, which is initially very frustrating, but eventually very apparent. Today I took the 7th test in the BB and there wasn’t one question that surprised me. They always have the cost function, the bar graph increase/decrease, the quadratic parabola, the permutation probability and so on. Get to know those types; analyse every question whether you get it right or not; if you can’t do it in seconds, you’re doing it wrong.</p>
<p>(Wow, do I go on!)</p>
<p>Just curious, but what was you score for the math section when you took your first practice test, and what did you get on your 7th practice test?</p>
<p>-5 (raw score of 49) on the first, -1 (53) on the 7th :D</p>
<p>To illustrate the results of practice, here are my Math results in the first 7 tests of the BB (I hate “hardwork”, but it works. :/)</p>
<h1>1 = -5</h1>
<h1>2 = -3</h1>
<h1>3 = -3</h1>
<h1>4 = -2</h1>
<h1>5 = -7 (October results were to come out, was too distracted to do anything)</h1>
<h1>6 = -2</h1>
<h1>7 = -1</h1>
<p>wow, good job! :)</p>
<p>:) Danke! I highly recommend Grammatix though, just because it teaches you the right (but controversial) attitude towards the test.</p>