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Morewood
I am a mature, service-oriented mathematician, experienced in leadership and the application of technologies. Currently, I'm working with the Yworld.com team trying to build a place to facilitate collaboration where everyone can truly pursue their passions.
Where do I get new wheels or tires (for hand truck)?
Where do I get new wheels or tires? I have a folding hand truck and the (solid rubber) tires are disintegrating. Can I get new tires or new wheels for it?
Specifications: about 7 inch diameter (including the tire: 5+13/16 inch diameter without the tire) 1.5 inches thick with a 1/4 inch axle. The truck is rated for 150lb, but the wheels do not seem to the limiting factor.
6 AntwortenMaintenance & Repairsvor 4 MonatenExact value of the Integral from 0 to 1 of Cos(Sin(pi*x))*Cosh(Cos(pi*x)) dx?
2 AntwortenMathematicsvor 7 JahrenProduct of perpendiculars from foci of an ellipse to any tangent?
For a given fixed ellipse, with a tangent line to any point on that ellipse, consider the perpendiculars from the two foci to that tangent. What can be said of the product of these two distances?
A messy analytic proof is not difficult, but can anyone find an elegant demonstration of the result?
1 AntwortMathematicsvor 8 JahrenWho is as Clever as a Canadian?
The Canadian Open Math Challenge recently asked Canadian high school students to find the ratio of the inradii of two triangles ADP and CDP, given that ABCD is a parallelogram, that the circle inscribed in ABC is tangent to AC at P, that AD+DC=3(AC), and that AD=DP.
Can you match our Canadian students and find that ratio?
1 AntwortMathematicsvor 8 JahrenIs Yahoo answers broken again?
After several answers carefully crafting my answer to a question, neither submit nor preview do anything but refresh the "What's your Answer" page. Really annoying! Having worked that hard, I'd like to submit my answer. Is there any other way?
3 AntwortenYahoo Answersvor 9 JahrenIntegrate [x f ⁻¹(x)] from 0 to √2, where f(x) = tan(x)sec(x)?
Just something I found fooling around. The answer is a nice number and there is a very simple (if round-about) way to evaluate it, but is it easy if you don't know that?
2 AntwortenMathematicsvor 9 JahrenPartitions into ALMOST equal rectangles?
In how many ways can N blocks be arranged into two rectangles so that the first rectangle is one unit wider than the second, which is one unit taller than the first?
The first value of N for which this is non-zero is 4 = 2×1+1×2. <count is 1>
The next N with a non-zero count is 7 = 3×1+2×2 = 2×2+1×3 <count is 2>
The first N with a count of 3 is 40 = 14×1+13×2 = 4×5+5×4 = 2×13+1×14
This question was originally asked by Izjed:
http://ca.answers.yahoo.com/activity?show=s4xnCYKV...
but went unanswered.
1 AntwortMathematicsvor 9 JahrenMy Birthday Problem (easy)?
It's my bithday today! Many years ago I got a bicycle for my birthday. Seven years ago that bike was half as old as I. But it's slowly catching up to me! Today the bicycle is four sevenths of my age. How old am I?
Serious problem solvers should leave this for the juniors and try my hard birthday problem:
6 AntwortenMathematicsvor 10 JahrenMy Birthday Problem (hard)?
If the probability of a birthday cake candle being defective is a constant, "p", with all candles independent, then the probability of a candle problem on my birthday cake at MY age can be written as a product of irreducible integral polynomials in "p", the largest of which has degree 42. How old am I?
(That is: irreducible over the integers.)
4 AntwortenMathematicsvor 10 JahrenIs this series well-known? Σ (-1)ⁿ τ(2n+1)/(2n+1)?
Where τ(N) is the number of positive integer divisors of N, including N.
http://planetmath.org/encyclopedia/TauFunction.htm...
Is it well-known (and can anyone provide a reference) whether the alternating sum:
Σ (-1)ⁿ τ(2n+1)/(2n+1) for n=0 to ∞
diverges or converges (and if so to what)?
{I think I know the limit, if it exists, but I'm still checking details of my proof. Changing the order of addition is very dangerous with infinite series!}
2 AntwortenMathematicsvor 10 JahrenAbelian subgroups all finitely generated but an Abelian quotient group not finitely generated?
Does there exist a (non-Abelian) group G such that any Abelian subgroups are finitely generated, with a normal subgroup H, such that the quotient group G/H is Abelian, but not finitely generated.
Alternatively, given an Abelian group, A, which is not finitely generated (like the rational numbers under addition), and some other group H (pick any group you like), can a (semi-direct) product of A and H be constructed whose Abelian subgroups are all finitely generated?
(This is an attempt to answer Stoops' question about whether solvable groups with only finitely generated Abelian subgroups must be polycyclic.)
1 AntwortMathematicsvor 1 JahrzehntSeeking the largest "Small Brain Number". Upper and/or lower bounds?
A small brain number is an "n" digit number equal to the sum of the n-th powers of its digits.
3-digit example: 153 = 1³ + 5³ + 3³
4-digit example: 8208 = 8^4 + 2^4 + 0^4 + 8^4
61 digits (or larger) is impossible since 61×(9^61) is only a 60-digit number.
Can we narrow down the gap?
This is a follow up to Riley's question:
4 AntwortenMathematicsvor 1 JahrzehntMake 100 using 1,2,3,4,5,6,7,8, & 9 with only add, multiply and concatenate?
Is it possible? Give an example or prove impossible.
The rules.
1) You can only use each digit ONCE
2) EVERY digit (except 0) must be used.
3) You can concatenate digits to make multi-digit numbers.
4) Only the operations of addition and multiplication are allowed.
(I.E: 2 and 3 can be turned into 23 or 32 or 2+3 or 2×3)
7 AntwortenMathematicsvor 1 JahrzehntHow should we handle duplicate questions, in keeping with community guidelines?
What should I have done to avoid a notice of violation of community guidelines?
After carefully answering a homework question, I noticed the same question (right down to topographical oddities) from two other users - all copy-pasted from the same original assignment? The three postings were all a week old and none had previously been answered, so I answered the other two by posting links to first answer. One of those two generated the violation notice, while the other is still in voting:
http://answers.yahoo.com/question/index?qid=201010...
(Anyone what to report it? Or vote for it?)
The only question I can find here about answering duplicate questions complains about duplicate answers. It was suggested (by Johnny Q) that answerers post links to earlier instances of the same question (or report them as abuse - but these seemed to be honest duplications, all posted at about the same time):
http://ca.answers.yahoo.com/question/index;_ylt=Ap...
I also referred each querent to the other two. (Email is preferable, but none allowed email.) Students in the same class with the same problem ought to seek help together. However other readers would not be interested. Would that be grounds for a violation?
Note: I did try to get feedback through the "customer care" link in the violation email. However the "Appeal Form" to which it leads appears broken today.
3 AntwortenYahoo Answersvor 1 JahrzehntIs the Yahoo! Answers Appeal Form broken?
I attempted to appeal a deleted question by filling in the Yahoo! Answers Appeal Form to which their email referred me:
http://help.yahoo.com/l/us/yahoo/answers/first_app...
However, the submit button merely reset the form to it's original blank state. On checking the page source, the "form" element lacks an "action" attribute. The current XHTML documentation ( http://www.w3.org/1999/xhtml ), to which the page header refers, states that this attribute is "REQUIRED" and no default action is provided.
I would report this apparent defect to Yahoo! Answers, but I cannot find a contact email (or other contact information) on the Yahoo! Answers site. Have I overlooked it?
2 AntwortenYahoo Answersvor 1 JahrzehntWhat question would properly be answered: "use perhaps the Riemann's dzeta function"?
I've seen that same answer next to the name Etienne de Quercy on every recent question where I've seen an answer from that name. Is that an abuse of this forum? (Etienne de Quercy has 94% "best answers" and that answer is getting multiple votes for best answer!) Has that account given any sensible answers?
Some examples:
http://answers.yahoo.com/question/index?qid=201007...
http://answers.yahoo.com/question/index?qid=201007...
http://answers.yahoo.com/question/index?qid=201009...
3 AntwortenMathematicsvor 1 JahrzehntWhat non-zero complex analytic functions have all derivatives non-zero, everywhere?
So for every complex number z, f(z)≠0 and all derivatives fⁿ(z)≠=0.
This is a followup to another question:
1 AntwortMathematicsvor 1 JahrzehntCan the sum of two positive rational numbers equal the ratio of the sums of numerators to denominators?
Normally this is not true: 7/8 + 2/5 is NOT equal 9/13. The same sum can be written 35/40 + 16/40, which is NOT equal 51/80 (which is also not equal 9/13).
Can it every be true? Examples? Or better, given two positive rationals, is there a procedure to write them in terms of (integral) numerators and denominators so that the sum of the rationals equals the ratio of the sum of the numerators to the sum of the denominators. Could the numbers be equal 7/8 and 2/5?
This is a follow up to :
http://answers.yahoo.com/question/index;_ylt=ApSDy...
where examples with negative rationals (and irrational imaginary examples) were given.
3 AntwortenMathematicsvor 1 JahrzehntCan the sum of two rational numbers equal the ratio of the sums of numerators to denominators?
Normally this is not true: 7/8 + 2/5 is NOT equal 9/13. The same sum can be written 35/40 + 16/40, which is NOT equal 51/80 (which is also not equal 9/13).
Can it every be true? Examples? Or better, given two rationals, is there a procedure to write them in terms of (integral) numerators and denominators so that the sum of the rationals equals the ratio of the sum of the numerators to the sum of the denominators.
This is a followup to:
http://answers.yahoo.com/question/index?qid=201007...
(Choice 3)
2 AntwortenMathematicsvor 1 JahrzehntWhat is the total number of sides on the loonies in the smallest non-trivial 6-pointed star?
A loonie is the Canadian 1 dollar coin which is not quite round, it is a hendecagon. There have been recent questions here about polygonal and stellar numbers, numbers of coins which can be arranged into filled-in polygons or stellated polygons (stars). Usually such arrangements begin with a single coin, the trivial case. I want a recognizable star, or what some might recognize as a snowflake pattern, so more that one coin is required. Count the total number of sides on the loonie coins required to make the smallest recognizable (and filled-in) six-pointed star.
Happy Canada Day!
2 AntwortenMathematicsvor 1 Jahrzehnt