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Forum: Challenge Questions and Puzzles

Have a challenging question or puzzle you want to share with the community? Post it here (homework questions do NOT belong here).

  1. Sticky Thread Sticky Threads

    • Replies: 2
    • Views: 2,301
    October 15th, 2017, 16:11 Go to last post
  1. Normal Thread Normal Threads

  2. Propositional calculus

    Started by solakis, May 11th, 2018 20:52
    callculus, propositional, prove, pwedgenot, pwedgenotqvee
    • Replies: 9
    • Views: 190
    May 20th, 2018, 23:58 Go to last post
  3. Unsolved Challenge
    Simple closed form for integral

    Started by Tony, April 23rd, 2018 15:04
    2pi1-ln2$$, closed, dt=ln2over, show, simple
    • Replies: 2
    • Views: 186
    May 20th, 2018, 22:52 Go to last post
    • Replies: 2
    • Views: 119
    May 20th, 2018, 22:50 Go to last post
  4. A Hankel Determinant Limit

    Started by June29, May 17th, 2018 19:54
    $ai, entry, hankel, matrix, show
    • Replies: 2
    • Views: 144
    May 18th, 2018, 18:48 Go to last post
  5. Challenge problem #4 [Olinguito]

    Started by Olinguito, May 12th, 2018 07:06
    $n$, flicks, lights, person, switches
    • Replies: 2
    • Views: 148
    May 15th, 2018, 12:11 Go to last post
  6. Challenge problem #3 [Olinguito]

    Started by Olinguito, May 5th, 2018 00:27
    $x=k$, challenge, curve, problem, tangent
    • Replies: 4
    • Views: 208
    May 13th, 2018, 20:04 Go to last post
  7. axiomatics

    Started by solakis, May 3rd, 2018 12:13
    2 Pages
    1 2
    a+b+c, a=/=0, a=b, axioms, e.t.c
    • Replies: 16
    • Views: 436
    May 9th, 2018, 13:35 Go to last post
  8. set theory

    Started by solakis, May 7th, 2018 20:40
    2εa, axiomatic, prove, set, theory
    • Replies: 3
    • Views: 142
    May 8th, 2018, 16:10 Go to last post
  9. Circumcircles

    Started by mrtwhs, May 7th, 2018 16:39
    ab=c, circumcircles, circumradius, hypotenuse, triangle
    • Replies: 2
    • Views: 152
    May 7th, 2018, 19:13 Go to last post
  10. Challenge problem #2 [Olinguito]

    Started by Olinguito, April 22nd, 2018 19:47
    $$5varphi_n^2+4-1^n$$, challenge, forall, perfect, show
    • Replies: 3
    • Views: 134
    May 1st, 2018, 19:50 Go to last post
  11. Loan @ 3 rates

    Started by Wilmer, April 29th, 2018 17:29
    apr, compounded, loan, monthly, rate
    • Replies: 8
    • Views: 163
    April 30th, 2018, 19:38 Go to last post
  12. Tanh Integral

    Started by Tony, April 24th, 2018 11:32
    dt=colorblue2ln, integral, prove, tanh, t^2mathrm
    • Replies: 1
    • Views: 87
    April 24th, 2018, 13:16 Go to last post
  13. Unsolved Challenge
    Integral of tan, ln

    Started by Tony, April 24th, 2018 02:21
    $$int_0^pi/2ln^2, integral, show, tan, tan^2
    • Replies: 0
    • Views: 68
    April 24th, 2018, 02:21 Go to last post
  14. Unsolved Challenge
    An interesting Integral

    Started by Tony, April 24th, 2018 02:05
    $$int_0^pi/2ln^2leftln^2, integral, interesting, prove, sin
    • Replies: 0
    • Views: 67
    April 24th, 2018, 02:05 Go to last post
  15. Unsolved Challenge
    Five, Phi and Pi in one integral

    Started by Tony, April 9th, 2018 16:56
    $$int_0piover, 2lnsin, integral, phi, xover
    • Replies: 3
    • Views: 158
    April 23rd, 2018, 17:52 Go to last post
  16. Unsolved Challenge
    Long Integral

    Started by Tony, April 23rd, 2018 03:24
    2right^2-2ln2over, dt=leftpiover, integral, long, show
    • Replies: 0
    • Views: 51
    April 23rd, 2018, 03:24 Go to last post
  17. Unsolved Challenge
    Integral of sine

    Started by Tony, April 22nd, 2018 18:31
    $$int_0^2pisinleftxover, 4rightsinleftxover, integral, prove, sine
    • Replies: 3
    • Views: 92
    April 23rd, 2018, 00:54 Go to last post
  18. Unsolved Challenge
    Integral of product

    Started by Tony, April 22nd, 2018 17:59
    912ln, dx=piover, integral, product, show
    • Replies: 0
    • Views: 55
    April 22nd, 2018, 17:59 Go to last post
  19. Challenge problem #1 [Olinguito]

    Started by Olinguito, April 22nd, 2018 03:54
    challenge, equation, quartic, satisfying, time
    • Replies: 4
    • Views: 89
    April 22nd, 2018, 07:43 Go to last post
  20. Unsolved Challenge
    imaginary integral

    Started by Tony, April 22nd, 2018 02:39
    $$int_0^2pimathrm, dtsin, imaginary, integral, prove
    • Replies: 1
    • Views: 74
    April 22nd, 2018, 04:19 Go to last post
  21. Unsolved Challenge
    Ahmad's Cousin - arctan integral

    Started by Tony, April 21st, 2018 16:17
    20$$, ahmads, cousin, dx=pi^2over, show
    • Replies: 0
    • Views: 76
    April 21st, 2018, 16:17 Go to last post
  22. Unsolved Challenge
    A tough Integral

    Started by Tony, April 18th, 2018 03:05
    $$mathrm, 1+t^4+t^8cdot, dtt-3t^3+t^5over, integral, ln-lnt
    • Replies: 6
    • Views: 217
    April 20th, 2018, 16:22 Go to last post
  23. Unsolved Challenge
    Quite complicated integral

    Started by Tony, April 20th, 2018 15:55
    $$int_0^inftycospi, 1over, 2+coshleftxpiover, complicate, x^2over
    • Replies: 0
    • Views: 66
    April 20th, 2018, 15:55 Go to last post
  24. Unsolved Challenge
    Curious Integral

    Started by Tony, April 19th, 2018 05:27
    curious, integral, pi^2+ln^2tan^2, show, xover
    • Replies: 0
    • Views: 65
    April 19th, 2018, 05:27 Go to last post
  25. Fish pond challenge

    Started by lfdahl, April 4th, 2018 22:08
    $r_f, $xt$, fish, fishing, fracx_04
    • Replies: 3
    • Views: 174
    April 14th, 2018, 15:05 Go to last post
  26. Maximum Displacement in Projectile Motion

    Started by Theia, April 12th, 2018 13:42
    alpha, dfg, tfrac12, time, v_0
    • Replies: 2
    • Views: 74
    April 14th, 2018, 13:25 Go to last post
  27. Unsolved Challenge
    A hard integral gives a simple closed form

    Started by Tony, April 10th, 2018 17:50
    closed, form, hard, integral, simple
    • Replies: 1
    • Views: 102
    April 10th, 2018, 23:28 Go to last post
  28. Unsolved Challenge
    Oloa Olivier's type integral

    Started by Tony, April 9th, 2018 06:05
    $$int_0^pi2$$, $$int_0^piover, integral, oloa, type
    • Replies: 0
    • Views: 99
    April 9th, 2018, 06:05 Go to last post
  29. Trigonometric product challenge

    Started by lfdahl, March 29th, 2018 14:54
    $$prod_j, challenge, product, prove, trigonometric
    • Replies: 2
    • Views: 119
    April 5th, 2018, 17:45 Go to last post
  30. Escape from the velociraptor

    Started by I like Serena, March 24th, 2018 07:43
    • Replies: 5
    • Views: 207
    March 28th, 2018, 12:06 Go to last post

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Top 89 Thread Starters For "Challenge Questions and Puzzles"

RankUser NamePercentage Of TotalThreadsMost Recent Thread
1anemone42.0748Solve for θ
2Albert20.1358find a,b
3lfdahl7.5133Fish pond challenge
4kaliprasad3.461irrational number
5ZaidAlyafey2.239Harmonic numbers identity
6MarkFL1.731Definite Integral
7Random Variable1.628A residue calculation
8sbhatnagar1.526Two Challenging Integrals
9jacks1.425Indefinite integration involvi...
10DreamWeaver1.324An inverse tangential problem
11solakis1.017Propositional calculus
12caffeinemachine0.815MHB's First Polymath Project.
12Tony0.815Tanh Integral
13Pranav0.713Summation challenge #2
14Wilmer0.611Loan @ 3 rates
15Krizalid0.610Continuity of IVP
15checkittwice0.610Determine all solutions in pos...
16I like Serena0.59Escape from the velociraptor
16greg13130.59Trigonometric Sum
16magneto0.59Sequence Challenge
17mathmaniac0.486n^3 + 3 is not a perfect 6th ...
17eddybob1230.48Increasing and Decreasing Numb...
18melese0.47Rational roots
18Rido120.47Find the limit (n!)^(1/n)/n
18hxthanh0.47Write n = a + b + c + ...
18mente oscura0.47Find the 6 reals roots
19CaptainBlack0.36Problem from Paper 3 of the 19...
19Bacterius0.36Divergence of a trigonometric ...
19soroban0.36The Missing intercept
19mathbalarka0.36A double sum challenge
19mathworker0.36pigeon hole proof
19Shobhit0.36An Infinite product
19Fallen Angel0.36Find all functions
20Poirot0.35Co-prime challenge
20sadsadsadsa0.35Ricky's Dinner
20jacobi0.35Probability challenge
20Theia0.35Maximum Displacement in Projec...
21Evgeny.Makarov0.24Game on a chessboard
21jakncoke0.24Putnam 2012: A5
21Olinguito0.24Challenge problem #4 [Olinguit...
22Also sprach Zarathustra0.23Integral of x^{-x}
22alane19940.23Einstein's Riddle
22Farmtalk0.23Secret Order
22The Lord0.23Integral
22Petrus0.23Differential Equation challeng...
22castor280.23Weird function challenge
23chisigma0.12A false approach to an integra...
23TheBigBadBen0.12Logic problem
23M R0.12Geometry Challenge
23Fermat0.12integration
23Euge0.12Abstract Algebra Challenge
23maxkor0.12Find the ACB angle
23Illmatic0.12Sum of reciprocals of roots
23jmprada0.12Sphere diameter
23June290.12Mutually commuting linearly in...
24The Chaz0.11Travelers and coins
24Prove It0.11Challenge: Is cos(pi/60) trans...
24Alexmahone0.11Hourglasses
24tkhunny0.11Missing in NY/PA
24Sherlock0.11Sum involving pi, ln(2) and Ca...
24Fernando Revilla0.11lim x ⌊1 / x⌋ , x...
24HallsofIvy0.11A geometric puzzle
24masters0.11Where's the father?
24DrunkenOldFool0.11infinite sum
24Opalg0.11Puzzle with digits
24Deveno0.11Identify the mystery group
24Amer0.11Nice Puzzle
24princeps0.11LCM Inequality
24Chris110.11Simple, fun puzzle
24QuestForInsight0.11Exponential limit
24topsquark0.11Sort of a challenge
24Petek0.11Unique Factorization Domains
24mssrki0.11Mathematics - a new basis
24johng0.11number of p subgroups
24judytl30.11Factoring over the Integers
24stainburg0.11Boring. Then Prove it!
24jeffer vitola0.11Limit is Sum
24individ0.11Solve triple square Diophantin...
24RLBrown0.11Next integer in this sequence,...
24Bibubo0.11divisibility and sums
24Dai0.11Puzzle
24Prakhar0.11Challenging Integral
24RobJob0.11The connected Game
24Monoxdifly0.11Arrange Mathematical Operation...
24mrtwhs0.11Circumcircles
24Joppy0.11Show that is the square of an ...
24bio0.11Year 7 & 8 mathematics puz...
24rick1230.11The Durango Curve Problem
24TheFallen0180.11Mathematical puzzle involving ...
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