Mathematics

Hi guys, Its been a while and my brain has gne soft, (blows the dust off the chess set). Right, I've got a LED it is a 2.5V at 11mA I've got a battery at 1.5V 1800mA How long would the battery last if the led worked at this low voltage. worked it out and I got some silly number, something like 43 sec's. Can someone show me the way this would be worked out so I know for the future. My cals were: (1.5 * 1.8)/(2.5 * 0.011) That says my led would only last 108s, my maths has gone!!! Jon.

If you project a helix onto a 2D plane from a perspective normal to its axis, what type of curve is the result, and what formula describes it? Another way of putting it: If I want to draw a side-view of a twist drill bit, how do I draw the flute? Thanks!

Ok for my homework tonight we had to do problems like these: I=?,P=12,000,R=7%,T=2years I=Intrest P=Principal R=rate T=Time I=83.00,P=6000,R=?,T=3years I got how to do those(IChose random numbers) But I need help trying to get I=125,P=?,R=6%,T=6years How do I get the principal? We never learned it in class

I'm trying to figure out the name of the theorem in which one sphere is cut into infinitely small pieces, and when put back together, it has the possibility of creating two spheres of the same volume as the original sphere. Can you help me?

Can anybody describe to be "in basic" terms what is a Platonic solid? And why are there only five? Also what does it mean to say that the faces, angles and edges are all congruent? Thanks

Consider an n-dimensional complex vector space. The corresponding vector space of nxn matrices is n^2 dimensional. I want to find out if there exists a basis for this space consisting of semipositive matrices. The question seems simple, but I can't find a proof. any help is appreciated.

An axiom to settle the continuum hypothesis ? (Logic Colloquium 2004 contributed abstract) Paul Cohen used a set of generic reals to prove the consistency of the negation of the continuum hypothesis with other axioms. It is my opinion that such sets do not really exist for a Platonist. My opinion is that the continuum hypothesis is true. Here is a tentative axiom from me to try to prove it. Axiom : An infinite subset of the power set of N has a bijection either with a countable union of (pair wise disjoint) sets of n elements or with a countable Cartesian products of (pair wise disjoint) sets of n elements. Mr Andreas Blass proved that this axiom is equiv…

Hi all, This is my first post in this section of the forums! I was doing some past papers and I am stuck in this question. Need help any1.I am not very good at maths! I am doing A’ levels by the way. Q. Solve the equation for angle in the range -180 ≤ Ф ≤ 180. 4 Cos2 Ф + 5 Sin Ф = 3 My solution is: 4 (1- Sin 2 Ф) + 5 Sin Ф -3 = 0. 4 – 4 Sin 2 Ф + 5 sin Ф -3 = 0. -4 Sin 2 Ф + 5 sin Ф = 0. Assuming sin Ф = x, then -4x2 + 5x + 1 = 0. Using quadratic formula: x = -b -+ √ b2 – 4ac 2a x = - 5 -+ √ 5 -4(-4)(1) -8 So x = -5 – 4.58 …

I spent a little bit of time yesterday looking at magic squares yesterday (something which I havent done since school) I noticed that sudoku puzzles are basicly magic squares but they reuse each number 9 times. Sudoku puzles are in essence very easy to make. Simple count up and loop back to 1 after 9. and offset each row so that it there is never the same number in each colum. 1 2 3 l 4 5 6 l 7 8 9 4 5 6 l 7 8 9 l 1 2 3 7 8 9 l 1 2 3 l 4 5 6 2 3 4 l 5 6 7 l 8 9 1 5 6 7 l 8 9 1 l 2 3 4 8 9 1 l 2 3 4 l 5 6 7 3 4 5 l 6 7 8 l 9 1 2 6 7 8 l 9 1 2 l 3 4 5 9 1 2 l 3 4 5 l 6 7 8 each number can be switched with any other and the order of the colums a…

One reason why the negation of the axiom of choice is true We apply set theory with urelements (non sets) ZFU to physical space of elementary particles; we consider locations as urelements, elements of U, in number infinite. Ui is a subset of U with number of elements n. XiUi is the infinite cartesian product and a set of paths. Let us consider the set of paths of all elementary particles-locations which number is n. If n is greater than m in CC(2 through m), countable choice for k elements sets k=2 through m, the set of paths will be the void set. So, after an infinite time, physical space would become void, the universe would collapse and a Big Crunch woul…

Dont tell me the answer but how easy is this to do? X = 3 √(X+3)3 - (X+1)3 + (X+8) 3 find X...

I have problem with getting normal coordinates offset. I have cube1 and cube2. cube1 position is 10,10,10 and cube2 position is 10,9,10. Cube 2 offset refers to local coordinate system of cube1. If rotation of cube1 is 0,0,0 i get position offset 0,-1,0. But if cube1 rotation is 45,0,0 i get offset 0,-0.7071,+0.7071. The problem is that offsets dont use normal coordinate system, they use local coordiante system of cube1. How do i get offsets on normal coordinate system?

A quick problem. Requires a little high school math reasoning. (x^2)(y) = x (z)(x) = y x, y, and z are not zero, +/-infinity, or +/- 1. Solve for x, y, and z. (there is a solution)

kudos for anyone who solves this. This pattern goes on forever: 0, 1, 1/2, 2/3... What would be the limit as the pattern approaches infinity. In other words, whats the last number in the infinitely long pattern? example: 1.9, 1.99, 1.999 evenly approaches 2.

I put this challenging puzzle in the “Brain Teaser and Puzzles” forum but nobody tried to solve it so far, so I decided to post it in this forum as well. I hope it does not amount to a “spam”.

A common way of constructing a pseudovector p is by taking the cross product of two vectors a and b: p = a × b. As x goes to −x, y to −y and z to −z, a and b go to −a and −b (by the definition of a vector), but p clearly does not change. Is it right to say that every vector is a pseudovector as per the above stated defination,as we can represent any vector as a cross product of two vectors?

So i had a trig test today, and my teacher marked off a problem, and ive reviewed it plenty of times, but cant seem to figure out what i did wrong. Could someone please help me with this, i am simply converting to standard form of an ellipse/hyperbola. The equation is x^2 + 4y^2 +2x +16y = -1 . I believe that my answer was something like ((x+1)^2)/4 + ((y+2)^2)/1 = 1 . I am not possitive if that was my exact answer, but i am sure the problem is exact. I think i got it right and just neglected to show some valuable piece of work, and my strict math teacher counted it off. Thx in advance for the help, and i appologize for not using latex, i was in a hurry.

Which of these two tend toward zero slower? In other words, which one will eventually remain larger than the other for all x greater than an arbitrary finite number? f(x) = 1/(x(lnx)^2) f(x) = 1/((ln(3^x))^2) Sorry for the prolific use of parentheses; I wanted to make the functions very clear.

Hi everyone! Lately at school we've been dealing with logarithmic inequations and they seem pretty tricky. So I was wondering if anyone could add a link or just post some useful hints that would help solving these inequations. I'd appreciate any kind of help!

If you can have commutative properties for an axiom such as A+B is equal to B+A does this mean physically in reality that at some extent all physical objects must at least have one thing in common? I mean A could be bob and B could be ann so you could say bob and ann is here and ann and bob are here right? On that note should you would not say annbob is here or bobann is here, so does equality in this sense merely apply to this existence in knowledge of bob and ann? Or what else is so fundamental about A+B=B+A that it can pertain fully or correctly to physical reality? Because to me for it to reach equality in another sense then applies at least a scope or scale to t…

Zero is equal to or greater than infinity......Right? wrong?

Can you get pi anywhere on the Klein bottle or are the two related in any way? I am just wondering being I don’t know much about the Klein bottle but I am wondering overall if it has any connection to irrational numbers then of course I though about pi.

How do you find the greatest common factor of a series of numbers with decimals?

Hi! I'm new here, and I don't know if this is the right place to ask, but here I go: I'm studying some maths and physics and I'm taught about the characteristics of the things but not about the reason why things are, this matter is considered up to my self so I speculate... Is there any relationship between the complex numbers and any rotational movement or something? is the "complex thing" related with any circumference specularly symmetric to the unitary one, but directing its ratio to the inside sense of rotational axes, such vectorial products...? in this situation I'm thinking of I'd understand the negative value of the square of "i"...What do you think about the…

Some time ago I came across a description of a numbering system for some very large numbers (mind boggling, in fact) that involved numbers written within triangles, squares, and circles. I know it was a shorthand for some exponential calculation, but can't remember exactly what it was, and I can't find the reference - it was in a random book in my local library. Any help? Thanks in advance.