<p>ahhh damn, I forgot to make some of them negative. yeah, this is a problem that definitely will take a while, no way around it.</p>
<p>x^2+y^2<9
integral solutions</p>
<ul>
<li> -2 -1 0 1 2<br>
-2 x x x x x
-1 x x x x x
0 x x x x x<br>
1 x x x x x<br>
2 x x x x x<br></li>
</ul>
<p>count all the x's. 25</p>
<p>you dont actually have to draw up the whole thing. You just need to acknowledge the symmetry that goes in to it. Its actually easier to do it by a graphical method. Draw the circle x^2+y^2=9 and check to see how many points with integral coordinates lie inside the circle.</p>
<p>ok heres one problem from yesterday's SAT that i didn't understand. it had to do with that circle with the dot in it, from the math section. instead of saying circle with dot in it, i will just say O.</p>
<p>for ab
a O b = ab + a + b</p>
<p>for xyz...</p>
<p>what the hell i dont get that? it was number 20 on the first math section.</p>
<p>x O y O z=xyz+x+y+z </p>
<p>I didn't take the SAT yesterday... but maybe..?</p>
<p>actually it was a I, II, III question, and that answer wasnt up there.. one was something like x O (yz) = blah blah</p>
<p>for that i guess you would go yz = y O z = yz + y + z</p>
<p>and then it would be x O yz + y + z = xyz + x + y + z</p>
<p>so yeah i think your right about that one, im just not sure how they wrote it.</p>
<p>here is 1</p>
<p>3,5,-5...</p>
<p>The first term in the sequence of numbers shown above is 3. Each even-numbered term is 2 more than the previous term and each odd-numbered term, after the first, is -1 times the previous term. Whats is the 55th term of the sequence?</p>
<p>A 5
B 3
C -1
D -3
E -5</p>
<p>I know if u do it the long way its easy, but i was wondering if there was a formula that could be applied?</p>
<p>is there a repeating pattern?</p>
<p>yes there is. 3, 5, -5, -3, 3, 5...</p>
<p>then i would start counting after the 6th number. lets just count by 6s, and each one will be a 5</p>
<p>6,12,18,24,30,36,42,48,54.. so if 54 is 5, then you need to find the number that comes after the the 6th number in that order, which would be 3. if you want to shorten it more, you can just say that 54 is the highest multiple of 6 and that would have a remainder of 1, so you just move 1 place over from the 6th number, which would be the first number.. gotit?</p>
<p>oh wait, i just realized that the pattern isn't 6 numbers like your last post, but its 4 numbers, so just do the same thing i just said, but with the highest multiple of 4 being 52, and then going over 3 places to get -5</p>
<p>Thanks taffy, i forgot about that trick. Although i got the problem right, it took me about 3-4 minutes to get to the answer and ur way it doesnt take more than 10 seconds</p>
<p>
<p>for xyz...
</p>
<p>I think the solution is like this
x O y O z = (x O y) O z
= (xy + x + y) O z
= xyz + xz + yz + xy + x + y + z</p>
<p>Can someone post a review of PROBABILITY? Like, what one should do in different situations, and maybe a couple of examples? </p>
<p>Thanks!</p>
<p>it didnt really have a solution, it was one of those I, II, III problems where its like which is true: I, I and II, I II and III, I and III, none</p>
<p>tm2000, post a probability question.</p>
<p>Oh, i see.
tm, your question is too vague. can you narrow it down or simply ask a question like taffy suggested.</p>
<p>probability =</p>
<p>the three classics</p>
<p>nCr
nPr
and ! <(factorial)</p>
<p>think of it in this way, nCr is for a lottery type probability when order DOESN't MATTER
and nPr is like a race when ORDER does matter</p>
<p>and factorial is the fundamental aspect of nCr and nPr. (8! = 8 * 7 * 6 ... * 1)</p>
<p>this is just a vague explanation..give an actual problem and I'll show you how to solve it in under a minute (any proability problem (supposedly the "hard" ones on the test can be solved in under a min)</p>
<p>post up.</p>
<p>can any1 explain to me #18 page 795 from the blue book? I am not even sure if circumference is being refered to the whole circle or the part.</p>
<p>And also #13 on 534</p>
<p>Thanks</p>
<p>Circumference always refers to the entire circle. So, for the whole circle, 18 (2+b) = 45 Distribute and get 18 b = 9 so b = .5</p>
<p>Now set up a proportion: .5/45 = x/360, so x = 4 degrees</p>