# Search results

1. ### Quick counting question

I'm on the verge of a solution but the computer lab is closing so I'll have to wait till tomorrow to post :frown:, sorry. Hopefully someone else will help out till then. They must mean arrangements of all possible sizes, since the total number of arrangements of size 25 is much much less...
2. ### Quick counting question

are arrangements of any size allowable? ie: 1 ball, 2ball, .... arrangements, or do they have to be a fixed size?
3. ### Question on Electricity

I'm not sure I'm the best person to answer this question, hopefully someone with more knowledge will come in and offer a more detailed answer, but for the mean time, The charges that develop from the glass/silk & plastic/fur systems are generated from the breaking of the molecules when you...
4. ### Need to get rid of the 'h' on the denominator

I'm purely joking, as far as I know, Leibniz and Newton discovered the idea independently of each other :smile: .
5. ### Need to get rid of the 'h' on the denominator

just to play devils advocate :devil: ... Sure, after he stole the idea from Newton! :tongue2:
6. ### Chemistry: Equilibrium

Yes exactly, Silver nitrate is soluble in water, but silver chloride isn't. So adding silver nitrate is like taking away chloride ions from solution...
7. ### Describe a circle as an ellipse?

Think of a circle as having 2 axis perpendicular to each other (like an ellipse) that both pass through the center. What can be said about their lengths? what is the equation of an ellipse, where does the length of the axis show up in that equation?
8. ### Easy calc problem

let I = \int sec^3xdx and let u = secx \ \ \Rightarrow \ \ du = secxtanxdx dv = sec^2x \ \ \Rightarrow \ \ v = tanx using integration by parts we have I = uv - \int vdu \Rightarrow \ \ I = secxtanx - \int secxtan^2xdx using the trigonometric identity tan^2 = sec^2...
9. ### Schools Advantageous of private schools

One real difference between private and public schools is the amount of personal care you recieve. I have friends that go to both public and private schools (I go to a public one myself) and the general concesus is that private schools treat you a little better. For example, private schools...
10. ### Frequency and wavelength!

Well there goes the chance of the OP doing any of the work for himself.
11. ### Frequency and wavelength!

1\f is the period, for wavelength you want to use the equation for all waves v = f \lambda where v is the speed of propogation of the wave
12. ### Decibel problem

hint: first find the distance from the radio the gardener would have to be to here an increase in intensity of 10dB A useful equation is the inverse square law for intensity \frac{I_1}{I_2} = (\frac{r_2}{r_1})^2 where I1 is the intensity at a distance r1, and I2 is the intensity at...
13. ### Stressed over nothing?

I would really like to second what mathwonk has said here. It has been my experience as well that above grades and test scores, teachers recognize genuine interest and effort to actually learning the material. This can go a long way. Of course I would not deny that society evaluates us...
14. ### Locus of points with distance sum =8

their talking about the sum of the distances from A and B. So you need to come up with an equation for the the distance from A and the distance from B seperatly, and then add them... that sum should equal 8 to see the motivation behind this problem look up the definition of an ellpise...
15. ### Book suggestion stickies?

very saddening, this is the only thread here that has 0 replies :frown: to the admin: I can't seem to delete the thread myself, so feel free to kill it whenever you like.
16. ### Im not sure how to answer LOCUS question

There is no set way of doing this, each problem is different, Generally you have to let your mathematical intuition guide you to the solution. I'll go through this problem in detail as an example. In this problem, You are given the condition that every point in the locus must be 3 units...
17. ### Im not sure how to answer LOCUS question

I apologize that my post was so terse, I thought that the hint from the first post I did would be enough to set you on your way. Perhaps your confused with what a locus is. A locus is a set of points satisfying a given condition. In this case, the condition is that everypoint in the locus...
18. ### Im not sure how to answer LOCUS question

plug in the distance for d, and the given point for (x1,y1) and then square it. What does that equation remind you of? This could have alternatively been done directly by using the equation of a circle, but doing it this way shows you where that equation comes from.
19. ### Im not sure how to answer LOCUS question

Your in a swarm of locus! :smile: Start with this one since it seems to be the easiest. what is the formula for the distance between two points? what kind of geometric figure contains points that are all the same distance from a fixed point (or center)?
20. ### Changing rates

Thats the right answer. Just to let you know, there is another way of solving this that lets you avoid having to find what theta is, by using the definitions of sec(theta) for a right triangle. cos \theta = \frac{A}{H} sec \theta = \frac{1}{cos \thet} = \frac{H}{A} \Rightarrow...
21. ### Changing rates

by the way... did the problem tell you that y doesnt change or is that your assumption? You get a different answer if z is constant.
22. ### Courses Heads up on Math courses

good to know :smile:
23. ### Changing rates

how did you come up with that answer? hint: your solving for \frac{dx}{dt} [/itex], so you need both the values of \frac{d \theta}{dt} and [tex] sec\theta
24. ### Book suggestion stickies?

Just a suggestion, but why not include a stickie near the top of each forum that gives a list of the most commonly recommended books? In just about every subject there are those classic well known books that everone seems to agree are the standard for that paricualar field. Is there some...
25. ### BS or BA?

sorry to interupt the flow of this forum, but I just have to know. what does IIRC stand for? I've seen it all over the place but haven't been able to decipher it. PS: I love your avatar MoonBear :Laughing:
26. ### Changing rates

yes, that was it... whats the answer you get now?
27. ### Changing rates

your solving for the wrong quantity... the question asks for the rate at which x increases. The rate of change of theta is already given. also your derivative is still incorrect,, there is a small error, do you see it?
28. ### Changing rates

from your post it seems that you are dealing with a right triangle where z is the hypotenuse, y is the adjacent, and x is the opposite, with z=5, y=4, x=3. your derivative is incorrect. tan is a function of theta, and theta is a function of time, so tan is actually a composite function...
29. ### Average velocity= displacement/time

yes that is absolutely correct. a person that runs around a circular track and stops where he began has zero average velocity but non-zero average speed.
30. ### Full Binary Tree question

I'll take a stab at it. I would try proving by induction on N by letting P(N) be the statement that for a full binary tree with N\geq1 leaves, it has 2N-1 nodes. starting with the simplest case (a tree consisting of a single node) we'll prove P(1). in this case #leaves = #nodes = 1...