Couple SAT Math problems...HELP

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1

<p>Got a few wrong in math and I dont understand how the answer is right or how you even get the problem, for the ones for which it applies, I even tried graphing it but didnt work....like the one below:</p>

<p>1) If -3<x<4 , which of the following is not included in the range of *f<a href="x">/I</a> = x^2 - 2?</p>

<p>a) 2
b) 5
c) 10
d) 14
e) 16</p>

<p>Ans: E</p>

<hr>

<p>This is a figure question, so i dont know how to put up the picture but here is the description: </p>

<p>Its a triangle with around 110 as it angle measure, but its not drawn to scale. On one side it is labelled A, B, C. B is the midpoint of AC and the other side of the trialge is C, D, E. D being the midpoint of CE. And it LOOKS like BD is parallel to AE but its not drawn to scale so....here is the question</p>

<h1>2) AB = BC = CD = DE = 5. If BD = 3, what is the perimeter of the quadrilaterial ABDE?</h1>

<p>a) 13
b) 16
c) 19
d) 26
e) 31</p>

<p>Ans: C --> How??</p>

<hr>

<h1>3) x - y = 5 and x^2 + y^2 = 15, what is the value of xy?</h1>

<p>a) -25
b) -5
c) -3
d) 3
e) 25</p>

<p>Ans: B</p>

<p>If you could get the right answes for these please post a process of how you did it, I was confused by these.</p>

2

<p>ans to question no. 3-----
a formula u need to know--- (x-y)^2=x^2 +y^2 -2xy
as x-y=5 so (x-y)^2=25
now put these values and easily u will come up with the right answer choice</p>

3

<p>Looks like I missed that there, thanks gluttony. If you could help answer other 2 that would b great! Thanks--</p>

4

<p>further explanation of que 3--------</p>

<p>(x-y)^2=25
x^2+y^2=15
(x-y)^2=x^2 +y^2 -2xy
so,25=15-2xy
or,2xy=-10
or,xy=-5
answer choice B</p>

5

<p>ans to the question 2-------</p>

<p>now,as B is the MIDPOINT of AC and D is the midpoint of CE so the line BD MUST be parallel to the other side of the triangle AE and BD=0.5 of AE (a theorem--"if the midpoints of two sides of a triangle is joined by an straight line then the joined line will be parallel to the other side of the triangle and it will be half of the length of the other side")
that means AE=6
so the perimeter of the quadrilateral will be BD+DE+AE+AB=3+5+6+5=19</p>

<p>so 19 is the answer,the angle 110 is given here to confuse u</p>

6

<p>ohh i threw in the 110, to make you guys visualize the pic or w/e but i took it as being parallel, but didnt know that --"it will be half of the length of the other side") so this is true in all cases right? okay thanks, now just gota figure out #1</p>

7

<p>ans to the question no. 1----
i can explain the answer in 2 ways.choose the 1 you like as an answer:</p>

<ol>
<li>f(X)=x^2-2,that means y=x^2-2,so x^2=y+2......in the answer choices the values of the probable y's are given,what you have to choose here is which one of the choices can't be the value of 'y'. if you put 16 as a value of 'y' then you will get x=4.24264,but look at the condition of 'x' : -3<x<4,so if u put 16 as y (the range value of the function),then the value of 'x' that u get won't go along with the condition of 'x'......thats why 16 can't be a range value of this function. u can try other answer choices and every time you will end up getting a value for 'x' that will go along with the condition for 'x' given</li>
</ol>

<p>explantion 2. as u can see,the highest value for x can be 4 (-3<x<4),so put this value in the equation and u will get f(x)=14, but in no way u can get a bigger value of f(X) than 14,so definitely,16 can't be the answer</p>

<p>use the explanation that suits you.....ask me if you have any problem</p>

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<p>i hope i have answered your questions</p>

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<p>by the way,i am not good in english,so pardon me if i have wrote anything wrong.....looking forward to get more problems from you</p>

10

<p>just as i finished solving #1, you put the solution up thanks a lot though. But I do have another question. For this I was able to get the answer right, but my methods were not the best and I dont really remeber them as they are not accurate. Please help with this problem:</p>

<h1>24) When making a latte, Lori will use steamed milk that is above 170 degrees, since it will not boil. She will also not use Milk that is below 150 degrees, since it will not foam. If t represents the temperature of steamed milk, in degrees, Fahrenheit, that she will NOT use, then an inequality that represents all possible values of t is :</h1>

<p>A) |t - 170| > 160<br>
B) |t - 160| > 10
C) |t - 150| > 10
D) |t + 170| > 10
E) |t - 160| < 10</p>

<p>Ans: B</p>

11

<p>"if the midpoints of two sides of a triangle is joined by an straight line then the joined line will be parallel to the other side of the triangle and it will be HALF OF THE LENGTH of the other side"----------this theorem is true for every and any kind of triangle,so u can use it without any further thinking.
if u still have question,i can prove this theorem for you.</p>

12

<h1>24) When making a latte, Lori will use steamed milk that is above 170 degrees, since it will not boil. She will also not use Milk that is below 150 degrees, since it will not foam. If t represents the temperature of steamed milk, in degrees, Fahrenheit, that she will NOT use, then an inequality that represents all possible values of t is :</h1>

<p>A) |t - 170| > 160
B) |t - 160| > 10
C) |t - 150| > 10
D) |t + 170| > 10
E) |t - 160| < 10</p>

<p>Ans: B</p>

<p>solution: she must use milk of temperature more than 170 degree,right? so let's say, she will use milk of 180 degrees.
now let's evaluate the answer choices:
a) |t-170|=| 180-170 |=|10|=10,which isnt >160....so its wrong
b)|t-160|=|180-160|=20,which is >10,so its the answer........u can try out other choices but i m confident that u will find out them wrong as we found out a) wrong</p>

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<p>Thankyou very much gluttony, I am sincearly thankfull for your help. Good luck with critical reading part of the SAT, if you havent heard of this site, Number2.com</a> :: Free Online Test Prep is a great site to improve and its free, but [url=<a href="http://www.smartdoodle.com%5DCATURA%5B/url"&gt;http://www.smartdoodle.com]CATURA[/url&lt;/a&gt;] is much better, but its down for the moment so once again thanks a lot.</p>

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<p>thank you very much for letting me know these sites.i am also grateful to you. if you have any more math problems i shall solve them happily,looking forward to getting more problems from you.
p.s.-you know what? last night hannah (a member of this forum) scolded me indirectly when i wrote in a thread that i would like to solve math problem for others as i think i m a bit good in math :( well, surely i m not the best,but i want to try :) i tutor some boys of grade 10 mathematics.my english is bad,sorry for that :(</p>

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<p>go gluttony! math genius~</p>

<p>haha ;D</p>

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<p>lol asian......i am not a genius.....</p>

<p>by the way,where from asia u r? i m from BANGLADESH</p>

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<p>i just had a dumb moment.....when i was looking at question 24 i completley left out the ablsolute sign so i was kicking myself cuase i kept geting e lol</p>

18

<p>i'm korean, gluttony (:</p>

19

<p>Additional math question. Well i got it right, but I want to verify if my methodology would be correct and reliable. </p>

<p>Note**: u = union../// n = intersection
15) For any three sets A, B, and C, A u (B n C) = </p>

<p>a) A</p>

<p>b) A n B n C</p>

<p>c) A u B u C</p>

<p>d) (A n B) u (A n C)</p>

<p>e) (A u B) n (A u C)</p>

<p>I got E..Correct answer is E. </p>

<p>My Method: A = {2,5,7} B = {1,2,3} C = {3,4,5}
So I sovled the question first. B n C = 3 So A u 3 = {2,3,5,7} --> Im looking for this</p>

<p>a) A = 2,5,7 {Wrong}
b) A n B n C = {2,3,4,5} WRONG
C) A u B u C = 1,2,3,4,5,6.....WRONG
d) (A n B) u (A n C) = 0 .. WRONG
e) (A u B) n (A u C) = 2,3,5,7 = RIGHT..(its also the last choice)</p>

<p>This seemed good to me, but can I also use this method?</p>

<p>Find A u (B n C)....</p>

<p>"A u" x B = (A u B)
A u x n = n prevails due to order of logical operations...i think
"A U" x C = (A u C)</p>

<p>Therefore "A u" x (B n C) = (A u B) n (A u C)...= Right answer & wayyy lesss work. Does anyone know if this is fool proof or did i just get lucky....It makes sense though.</p>

20

<p>
[quote]

24) When making a latte, Lori will use steamed milk that is above 170 degrees, since it will not boil. She will also not use Milk that is below 150 degrees, since it will not foam. If t represents the temperature of steamed milk, in degrees, Fahrenheit, that she will NOT use, then an inequality that represents all possible values of t is :</p>

<p>A) |t - 170| > 160
B) |t - 160| > 10
C) |t - 150| > 10
D) |t + 170| > 10
E) |t - 160| < 10</p>

<p>Ans: B

[/quote]
</p>

<h1>24 is weird, can anyone explain this further? If t represents the temperature of milk that she will NOT use, then wouldn't you substitute a value such as 140 degrees, not 180 (what gluttony said)?</h1>

<p>So if you sub in 140, you get:</p>

<p>A) |140-170| > 160 - Wrong
B) |140-160| > 10 - Ok
C) |140-150| > 10 - Wrong
D) |140+170| > 10 - Ok
E) |140-160| < 10 - Wrong</p>

<p>So only B) and D) work, but how do you eliminate D), since B) is apparently the correct answer?</p>