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How about a glossary that explains mathematical terms and symbols so we can follow discussions that may involve Maths topics that we may not have had yet. I've found that just because I haven't taken a class in a topic does not mean it is beyond my comprehension. Yet, if I don't understand the terminology used in a particular thread, it is nearly impossible to follow.
What do others think about this?
When I went back to college after being out of school for ten years, I knew I had my work cut out for me. I tested into College Algebra, which was essentially the same material as the most advanced maths class I took in high school.
One of the requirements for this course, in addition to the textbook, was a graphing calculator. A TI-86 or equivalent was specified. So, I went calculator shopping.
Being an impoverished college student planning on taking lots of maths classes, I didn't see any sense in purchasing a TI-86 when I could get a TI-89 for about 15% more, and it had many more functions. So, I purchased the TI-89.
That TI-89 has been the best learning aid I could have hoped for. It does pretty much everything I needed to learn to do through multi-variable Calculus and most differential equations that I was expected to learn to solve.
Many times late at night doing homework, when I didn't understand a concept, I could break down a problem to see how solutions changed when I changed a single aspect of the problem, such as changing a constant or an exponent. This allowed me to see many patterns in the problems, and ultimately led to a deeper understanding of the material.
I don't particularly like doing Mathematics, but I am fascinated by all the stuff I can do with Maths. Therefore, I often take the lazy route and use my calculator find my derivatives and anti-derivatives, as well as messy arithmetic. Don't get me wrong, I can do these by hand (most of the time), but I find it's usually a pain, and significantly increases the likelihood of me making a stupid or careless mistake.
Now, I'm the first to admit that if you present me with a complicated integrate by parts problem, I'm going to struggle without my magic box. I don't do such problems by hand often enough to stay current. However, I am also aware that I live in a world where it is becoming increasingly likely that I can find a computer or a calculator before I can find a pencil and a piece of paper.
The vast majority of the Maths instructors I have had have all had a negative view towards calculators. They tend to believe that using a calculator as a learning tool is about teaching keystrokes instead of teaching concepts. I, on the other hand, believe that learning the mathematical concept is wholly different than learning the syntax used to solve the problem, whether it be with a pencil and paper or a calculator.
The calculator does the calculations for me. It does not know how to set up the problem so that I get the correct information as a solution. No matter how many functions my calculator has, if I don't understand the concepts behind those functions, the calculator is useless.
I've had this discussion with every single Maths instructor I've had in college. Only one has come remotely close to agreeing with me, yet not a single one has offered any logical counter argument, usually relying on the outdated "what if you don't have a calculator" response. Yet on occasions where I sought Calculus help from, for example, a Pre-Calculus professor, she was unable to assist me as it had been so long since she had done any Calculus exercises.
I feel we are fast approaching a time when pencil and paper syntax is completely outdated. I also think that many students would understand concepts more easily if teachers embraced calculators in the classroom instead of relying on traditional methods.
How do you feel about calculators in the classroom? Are they common learning / teaching tools in other areas? (I'm in central Florida, USA)
I could hide a hint or two if people wanted. The solution is VERY counter-intuitive. Had I not read the logic behind the solution, I never would have believed it.
40, 0, 0, 30, 30
Please try again.
Nifty. Near the end of the article, it speculates about Petabytes becoming available in the future.
What would a home user do with petabytes of storage? I can't conceive of a use for all that storage...except one: a versioned file system.
When I was just out of high school, my best friend, who was definitely a computer geek, claimed that no one would ever need a Gigabyte of hardware space. I had a 100 megabyte HDD which was considered pretty big.
Currently the LAN where I live (2-3 people at any given time) has about 2 Terabytes of hard drive space. I doubt there is a Gigabyte of free disk space on the entire network, and we still have plenty of CDs, movies and applications that remain to be saved to the hard drive.
It won't be that long before a TB isn't considered much space.
Zach, MathIsFun, those answers are incorrect; please try again.
(I am interested in the logic you used to obtain those answers, though.)
The correct answer is rather non-intuitive.
Five pirates return from a mission of murder plunder on the high seas. They have 100 gold pieces that need to be divided amongst themselves.
The pirates, conveniently named A, B, C, D, and E have a seniority order. Even more conveniently, A is at the top of the list, followed by B, then C, D, and E.
The highest seniority pirate gets to propose how the gold is split, and then the whole group votes to approve of the split or not. The high seniority pirate gets 1.5 votes, and the other pirates get one vote. If the proposed split is approved, the gold is split up accordingly. If the proposed split is not approved, the high seniority pirate is killed by the other pirates, and the highest seniority of the remaining pirates get to propose the split, with the same rules.
All the pirates are rational.
How does Pirate A propose to split the 100 gold pieces to get the maximum amount for himself, while ensuring the proposal will be approved by vote?
Yes, but you're assuming that light obeys the same laws of physics as everything else. According to the laws of physics, nothing can reach the speed of light, so light's broken that one already!
Someone correct me if I'm wrong, but I believe relativity implies that the speed of light is a barrier that cannot be crossed. Photons either travel at the speed of light, or their energy absorbed into matter. They have not broken the barrier.
Also, there is nothing to suggest that there are no particles that travel faster than the speed of light (tachyons). Relativity says if those particles exist, they cannot accelerate (slow down) to the speed of light.
A college professor asks for two volunteers. Mary and John come forward.
The professor hands each of them an envelope. He tells them that there is money in each envelope. He explains that one envelope has twice as much money in it as the other, and that he will give the students the option of either keeping their envelope, or trading it for the other envelope.
Mary looks in her envelope and sees that there is a $10 bill. She thinks to herself: "If I trade it for John's envelope, there is a 50/50 chance that I will end up with $5 and a 50/50 chance that I will end up with $20. That means that I will either lose $5 or else I will gain $10." She reasons that this is the same as getting two to one odds on a 50/50 bet. In fact, if she were to get this opportunity 100 times, she would expect to lose 50 times and to win 50 times, thus ending up with a large, net gain. So she agrees to exchange envelopes.
At the same time, John goes through the same thought process, and he also agrees to exchange envelopes.
So the question is: How can they both be right?
Let X = total money in each envelope.
There are two possible cases. Mary will receive (1/3)X and John receives (2/3)X
or
Mary receives (2/3)X and John receives (1/3)X
If Mary receives (2/3)X by trading she can expect to gain (2/3)X or lose (1/3)X.
If she receives (1/3)X, by trading she can expect to gain(1/3)X or lose (1/6)X.
The reality is that the potential gain and loss is always (1/3)X of a total X.
Every time Mary loses, she has overestimated the total amount in the envelopes and the potential winnings by a factor of two. Every time she wins, she has overestimated her potential loss by a factor of two.
A better way for Mary to examine the probability would be to assume that since any given time, her envelope contains either ((1/2)+(1/6))X or ((1/2)-(1/6))X, on average her envelope will contain (1/2)X, and by trading or not each participant risks (1/6)X at even odds, such that the "pot" on any given transaction equals (1/3)X. Her risk analysis is not skewed by looking at the problem in this manner.
The potential winnings for either player in any round are a function of the total amount X, and not the amount in either individual envelope.
I saw a post on another forum yesterday from a grad student who is planning on doing his dissertation on Graph Theory and billiards strategy. I found that pretty fascinating.
An integration bee sounds challenging, Zhylliolom. I don't do much integrating these days. If I don't have the integral memorized, I use my trusty calculator.
Prove that any positive integer can be expressed as a sum of terms in the Fibonacci sequence without using any term more than once.
For example:
161803 = 121393 + 28657 + 10946 + 610 + 144 + 34 + 13 + 5 + 1
These are the 26th, 23rd, 21st, 15th, 12th, 9th, 5th and 2nd terms in the Fibonacci sequence.
Can anyone tell me the nth term for the fibonacci sequence and how you work it out please?
Thanks
The Binet Formula:
(((sqrt(5)+1)/2)^n-(-1)^n*((sqrt(5)-1)/2)^n)/(sqrt(5))
Here is a good page to get a look at the formula in a nicer format.
R=25
L=Sqrt(50^2 +60^2)
L is the length of the airplane hanger from front to back in my explanation. What is that length? Is it given as SQRT(50^2 + 60^2)?
X is the length of the rope.
BTW, what maths class is this for?
Zhylliolom: Also a good idea, but can't be done with the current forum software (PunBB). But Rickard Andersson is working on v1.3 which may allow it. So it may be possible about the time it is needed
What if exercises were removed from "Teaching Maths and given their own section so that there could be Algebra, Trig, Differential Calculus, Integral Calculus, Differential Equations, etc forums?
If I told you the real reason we don't use "perpendicular", it would scare you witless!
Do tell. I'm not that easily frightened.
Q2 A rope is stretched tightly over an plane hangar from A to B. The shape of the hangar is semi-cylindrical. Find the length of the rope.
Shape is sorta like that with A at one end and B on the other.
Since the rope is stretched tightly over the hangar, and point A is on one end of the hangar and point B is on the other end of the hangar, we can assume that point A and point B are on opposite corners of the hangar.
Again, the Pythagorean Theorem is the tool we need to solve the problem.
Let us call the length of the rope X.
Let us call the length of the hangar, from front to back L.
Let us call the width of the hangar at the base D.
D/2 = R
Note that R is the radius of the cylinder the hangar is based upon.
The Pythagorean theorem tells us: X^2 = (Pi *R)^2 + L^2
So X = sqrt((Pi * R)^2 + L^2)
Plug in the values for the variables (remember that R = D/2), and solve the expression.
how do i solve (22/4)^3/2??? without using a calculator
(11/2)^3/2 = 11/2 * sqrt(11/2) = 11/2 * sqrt(11) / sqrt(2)
If you are going to be doing maths without a calculator, I would highly recommend committing to memory or a reference table the square and cube roots of the first ten or more primes. Personally, I prefer the calculator
In this particular case:
sqrt(11) = ~3.31662
sqrt(2) = ~1.41421
11 * sqrt(11) / sqrt(2) = ~25.7973
Sudoku. . . Is Sudoku math-related though?
If we're talking math-related though, I guess Addoku puzzles (a popular, traditional Sudoku puzzle variant).
I think Sudoku is math related. Math is logic in it's purest form, right?
I've never tried any variants of Sudoku.
I know a bunch of these, but I'll wait to post any answers.:P:P
My favorite math related game is pocket billiards (commonly called pool in the US). I've been playing the game for about 25 years. It seems everything about that game screams Math and Physics, even in equipment selection (and production).
In a typical game, I use Trigonometry and the Pythagorean theory several times each, and constantly draw upon what I know about rotational Physics. Math even helps me to understand the best place to grip my cue on any given shot.
I can't actually think of any aspect of the game that cannot be learned more easily with an understanding of Mathematics and Physics, with the possible exception of the concentration necessary to make many consecutive shots.
I believe that a billiard table is quite possibly the most perfect piece of Math and Physics lab equipment. It offers the opportunity to teach many, many concepts from basic counting to Differential Equations all while allowing students to feel like they are having fun instead of doing school work. One of my goals for the future is to make these lessons more accessible for both students, and non-playing teachers, as well as to help increase accessibility to pool tables in schools.
What Math(s) related games do you like?
Benford's Law
Benford's law states that the probability P that digit D appears in the first place is given by (logarithm base 10):
P = log (1 + 1/D)
Therefore, for D = 1
P = log (1 + 1/1) = log (2) = 0.301,
For D = 2
P = log (1 + 1/2) = log (1.5) = 0.176,
And so on. For D = 9
P = log (1 + 1/9) = log (1.11. . .) = 0.046
The more general law says, for example, that the probability that the first three digits are 1, 5, and 8 is:
P = log (1 + 1/158) = 0.0027
The above was copied verbatim from The Golden Ratio by Mario Livio p. 267 (C) 2002 Mario Livio ISBN: 0-7679-0816-3
This property can be useful in accounting / finance.
A couple still remain...
Should I post more to keep this thread going?
Of course.
7. Jenn is facetious. She is also abstemious. She gets pneumonia. Given those clues, what is the only American tree she will like?
I do have a picture but I dun know how to put it in without loading the picture of the internet.
Do the circles touch each other at exactly one point? If not, my solution is incorrect and we need more information.