<p>Yea, post a specific example.</p>
<p>:)</p>
<p>If 4x=6u=5v=7w>0, which of the following is true?
a. x<v<u<w
b. x<u<v<w
c. x<v<w<u
d. w<u<v<x
e. u<v<w<x</p>
<p>D</p>
<p>first arrange it in order from least to greatest ( or greatest to least).</p>
<p>4x= 5v = 6u = 7w</p>
<p>then apply the inverse proportion law. That is after you set two equations equal to each other, and on one side increase the variable (or coefficient), the other variable on the same side decreases.</p>
<p>very wordy sorry.</p>
<p>Ok, first ignore the >0 part cause that just means that all the numbers are positive. Next, look at the first equation:</p>
<p>4x = 6u</p>
<p>Clearly, x>u so cross off a, b, and c. The third equation:</p>
<p>5v = 7w</p>
<p>This time v>w, so only choice d works.</p>
<p>Major shortcut:</p>
<p>In a equation like 4x=6u=5v=7w, the largest variable will be the one with the smallest coefficient (which makes sense intuitively) and vice versa, so the order is x>v>u>w (choice d, but you have to be careful about the use of > or <).</p>
<p>:)</p>
<p>Uh… inverse proportion law? <em>dumbfounded</em></p>
<p>Hm, this wasn’t a good one because I didn’t use any math to answer this question, either. Let me find a different one.</p>
<p>I have another tip. Whenever there is a question like x(some #+some #)(more numbers)=0, x is always 0. Yah, that probably wasn’t helpful to anyone. XD</p>
<p>Alright, here’s one.</p>
<p>If p, r, and s are three diff prime numbers greater than 2 and n = p x r x s, how many + factors, including 1 and n, does n have?
(this one ain’t MC)</p>
<p>Here’s one more.</p>
<p>If x <(or equal to) x <(or equal to) 8 and -1<(or equal to)y<(or equalto) x, which of the following gives the set of all possible values of x y? (all the <, > signs have ‘or equal to’ things on 'em too)</p>
<p>a. xy=4
b. 0< xy < 24
c. -1< xy < 11
d. -1 < xy < 24
e. -8 < xy<24</p>
<p>inverse proportion just means as you increase one variable (or coefficient), another variable always decreases</p>
<p>the prime answer is 5 right? </p>
<p>too lazy to work the other one</p>
<p>I think the factors of n are 1, p, r, s, pr, rs, ps and prs (=n), so there are eight of them</p>
<p>For the second one, is the problem x <= 8 and -1 <= y <= x (where <= means less than or equal to)? If so, wouldn’t the answer be -8 <= xy <= 64 ?</p>
<p><= wow I forgot that! XD</p>
<p>Oh, wow that makes sense tanman (ur first answer). Thanks.</p>
<p>Could you explain the -8 < xy < 64 solution, tanman? Thanks.</p>
<p>Wouldn’t you just choose answer e because you automatically know that -8≤xy≤(even though this should be 64) must be correct since this is the only answer that start with the -8?</p>
<p>Sorry! I think I wrote it wrong.
0<x<8 amd -1<y<3</p>
<p>Ugh, I dn’t know whats wrong with me.</p>
<p>Bumpityhumphump</p>
<p>-1 x 8= -8 and 8 x 3= 24
Therefore
e. -8≤xy≤24</p>
<p>You know ranges for x and y and you want to find the range for x*y. Since one of the terms can be negative (y), then you know that the lower bound for xy is negative. To find this lower value, take the smallest possible value for y (-1) and the largest possible value for x (8). If you had a situtation where both x and y could be either positive or negative, then you would have to check both max x * min y and max y * min x to see with gives a more negative value.</p>
<p>To find the max of the product xy, simply multiply the max of x * the max of y. Again, if both x and y could be negative, then you would have to check max x * max y and min x * min y to see which one was larger (remember that a negative times a negative gives a positive).</p>
<p>So you end up with E, -8 < xy < 24.</p>
<p>Yeah, I got E.</p>
<p>You take the smallest and largest extremes for both x and y and multiply them.</p>
<p>0 * -1 = 0
0 * 3 = 0
8 * -1 = -8
8 * 3 = 24</p>
<p>The lowest number is -8 and the highest is 24, so the range is -8 <= xy <= 24.</p>
<p>bumpityhumphump anymore advice for math in general?</p>