Sat Math Question

Test Preparation SAT Preparation
1

<p>Barrons Math Page 124 #10 if anyone owns the book.</p>

<p>If 1/p+q=r and p not = to q, what is p in terms of r and q?</p>

<p>(A) rq-1/q
(B)1+rq/q
(C)r/1+rq
(D)1-rq/r
(E)1-q/rq</p>

<p>I know that the Barrons has an answer explanation section, but I had a question about this. Say I run into a similar problem on the sat, and I don't know a fast way to solve it and/or take an educated guess, should I just skip it? And if any of you know a faster way, please include that in your post. That would be very helpful. Thanks.</p>

2

<p>im not sure if theres a rule that says u can just 'flip' the equations, 1/p+q=r becomes p+1/q=1/r, which is p=1/r-1/q, obviously it doesn't work lol. anyway so lets dso the algebra.
OK.
1/p+q -> 1/p + qp/p = r (common denominator)yes? good
(1+qp)/p=r, cross multiply.
1+QP=RP
1=QP-RP
1=(Q-R)P
1/(Q-R) = p
tadah!
is it in the choice? lol
why's not in the choice T_T</p>

<p>actually,what i did up there is accurate,but ineffient, heres a better way:
1/P+Q=R
1/P=(R-Q)
1/(R-Q)=P
if u're having trouble understanding, take this as an example:
6/2=3
6/3=2 , switch the divisors or w/e u call them,the one being divided.
good.</p>

3

<p>1/r to find p+q
1/r= p+q</p>

<p>we want P, so</p>

<p>1/r-q = P
1/r-q = 1-rq/r
thus 1-rq/r = P.</p>

<p>Answers D.</p>

<p>Am i correct?</p>

4

<p>If there is only one equation given and it ask you to solve for one unknown. Usually just pretty much solve for that unknown and disregard in terms of whatever because it comes out in that term anyway. </p>

<p>Whatever that previous advice is not good, but that's how I go with it.</p>

<p>After taking Calc 3, I pretty much know a lot of strange ways to mess around with equations. But since the SAT is definitely not that high up (pre-calc max?), I'd recommend you how to do several key things.</p>

<p>Cross Multiply</p>

<p>Adding fraction that doesn't have a common denominator. (example : 1/x + 1/(x+1) = (2x + 1) / (x^2+x)</p>

<p>Then pretty much it, if you got the basics down such as factoring, complete the square (you have a calculator so don't sweat on this), and most basically how to do the same operation to both sides.</p>

<p>-</p>

<p>Back to the question</p>

<p>but first PLEASE disregard Ren the SAT'er </p>

<p>"1/p+q -> 1/p + qp/p = r (common denominator)yes? good"</p>

<p>That is NOT doable. When your denominator is an addition, there is no easy way to split it. His equation comes out to be 1+qp/p = 1/p + p/r That doesn't equal what you were given.</p>

<p>My way:</p>

<p>1/(p+q) = r --> just dont sweat it, solve for p and you are done!
1 = r(p+q) --> multiply both sides by (p+q)
1 = rp + rq --> distributive property
1-rq= rp --> get rp by itself
1-rq/r = p --> divide by r</p>

<p>Answer D looks like what I got.</p>

<p>Anyway I do not recommend the number substitution method by SAT'er Ren because you can never distinguish something like (totally hypothetical) 1/p or p/1 where p = 1. I tried that on a practice problem and that totally didn't get me the wrong answer (gave me the flipped version)</p>

<p>If you have a TI-89 (highly recommend.), punch in solve(<equation here="">, p)</equation></p>

<p>Voila!</p>

5

<p>Ren the SAT'er, I'm sorry if you've misread my problem. 1/p+q=r, the 1/p+q is one fraction.</p>

6

<p>Oh he was not wrong in his own perspective then ;) </p>

<p>Disregard my disagreement with his method. But remember you could make that mistake, so try to avoid it =)</p>

7

<p>NadieN, MayBe you ShOulD CoNsUlt with the BlUe BOOk and SeE whAT The DiFFerenCe iS BetWEEn tHe TWo.</p>

8

<p>^ , now what's the point in typing like that? I understand this is the internet and everyone is entitled to their rights of doing whatever the hell they want, but please-for cb sake- don't type like that. Its irritating to read.</p>

<p>Each time you TyPe LykE ThIs , God lowers the curve for standardized tests.</p>

<p>Just kidding.</p>

<ul>
<li>Yay i got the right answer, i may not be a troll mathematician after-all!</li>
</ul>

9

<p>err... lower the curve and it's better for us?</p>

10

<p>it doesn't make much of a difference overall since the curve somewhat serves as an equalizer for all the scores, but having a generous curve sure makes our scores look slightly more impressive.
It was a typo, i meant increase.
good catch.</p>

11

<p>i did not misread; u mistyped.
lol.
oddly enough,i dont know how you guys can interpret 1/P+Q as 1/(P+Q),
1/P + Q is simply 1 over P, then plus Q, if u were to punch that in your calculator, u'd be wrong. u need parentheses, so in a way, you're all wrong,because you guys actually misread,but misread+ mistype= correct, IRONIC NO?
lol</p>

12

<p>lol when I read it the first time I read it as 1/(P+Q).</p>