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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: 1,884
    October 15th, 2017, 16:11 Go to last post
  1. Normal Thread Normal Threads

  2. Unsolved Challenge
    Prove (a-b)ᵃ⁻ᵇaᵃᵇ⁻ᵃ ≥ (a-1)ᵃᵇ⁻ᵇ

    Started by anemone, October 19th, 2017 11:38
    $a$, $b$, a-bᵃaᵃ, positive, prove
    • Replies: 0
    • Views: 46
    October 19th, 2017, 11:38 Go to last post
  3. sequences

    Started by solakis, October 1st, 2017 10:58
    1^n, diverges, prove, sequence, sequences
    • Replies: 8
    • Views: 239
    October 17th, 2017, 20:17 Go to last post
  4. triangular relations

    Started by solakis, October 17th, 2017 18:33
    ad^2+de^2+ae^2=, bd=de=ec, points, prove, triangular
    • Replies: 0
    • Views: 35
    October 17th, 2017, 18:33 Go to last post
  5. Unsolved Challenge
    Evaluate ∠APR

    Started by anemone, October 14th, 2017 02:19
    $angle, apq=3angle, apr$, evaluate, triangle
    • Replies: 3
    • Views: 127
    October 15th, 2017, 04:16 Go to last post
  6. Unsolved Challenge
    Prove √(sinx)>sin√(x)

    Started by anemone, October 15th, 2017 00:20
    $sqrtsin, √sinxsin√x, prove, sqrtx$, xsin
    • Replies: 0
    • Views: 79
    October 15th, 2017, 00:20 Go to last post
  7. Trig Inequality

    Started by lfdahl, October 4th, 2017 17:21
    $$5x, 8sin, inequality, show, trig
    • Replies: 2
    • Views: 125
    October 14th, 2017, 15:40 Go to last post
  8. Find the maximal value of the sum

    Started by lfdahl, October 8th, 2017 14:36
    find, maximal, numbers, real, satisfying
    • Replies: 1
    • Views: 88
    October 14th, 2017, 15:22 Go to last post
  9. Unsolved Challenge
    Prove ∠A≤60.

    Started by anemone, October 13th, 2017 12:28
    attempt, challenge, interesting, prove, unsolved
    • Replies: 2
    • Views: 128
    October 14th, 2017, 12:24 Go to last post
  10. TikZ Challenge 3 - Vector Diagram

    Started by I like Serena, September 26th, 2017 16:43
    challenge, create, picture, submission, tikz
    • Replies: 2
    • Views: 124
    October 9th, 2017, 11:04 Go to last post
  11. Find The Sum

    Started by lfdahl, October 3rd, 2017 14:16
    evaluate, find, sum
    • Replies: 2
    • Views: 120
    October 5th, 2017, 14:52 Go to last post
  12. Binomial sum

    Started by lfdahl, September 27th, 2017 15:41
    $$s_n, =sum_k=0^n-1^k3n, binomial, evaluate, sum
    • Replies: 2
    • Views: 128
    October 4th, 2017, 16:01 Go to last post
  13. Ratio of determinants

    Started by lfdahl, September 30th, 2017 15:31
    $$[beginvmatrix, c_k+1, c_k+2, determinants, ratio
    • Replies: 2
    • Views: 135
    October 3rd, 2017, 13:06 Go to last post
  14. proving a formula

    Started by solakis, September 28th, 2017 17:41
    axists, prove, proving, wedge, xin
    • Replies: 3
    • Views: 99
    September 30th, 2017, 11:15 Go to last post
  15. Definite integral to be evaluated

    Started by lfdahl, September 23rd, 2017 14:08
    • Replies: 3
    • Views: 133
    September 29th, 2017, 15:15 Go to last post
  16. Polygon sum challenge

    Started by lfdahl, September 27th, 2017 16:03
    $n$-gon, $s_n$, find, polygon, sum
    • Replies: 6
    • Views: 151
    September 29th, 2017, 15:11 Go to last post
  17. TikZ Challenge 2 - Function Graph

    Started by I like Serena, September 5th, 2017 18:49
    create, picture, submission, thread, tikz
    • Replies: 2
    • Views: 123
    September 26th, 2017, 16:42 Go to last post
  18. Poll: TikZ Challenge 1 - Geometrical Diagram - Votes

    Started by I like Serena, September 5th, 2017 18:09
    coordinate, left], node[above, node[below, path
    • Replies: 1
    • Views: 163
    September 26th, 2017, 16:39 Go to last post
  19. Definite Integral

    Started by MarkFL, September 24th, 2017 15:26
    definite, evaluate, i=int_0^infty, integral, xe^axcosx
    • Replies: 4
    • Views: 184
    September 25th, 2017, 19:07 Go to last post
  20. smallest number

    Started by kaliprasad, September 19th, 2017 06:51
    digits, divisible, made, number, smallest
    • Replies: 1
    • Views: 112
    September 25th, 2017, 07:34 Go to last post
  21. find n

    Started by kaliprasad, September 19th, 2017 10:15
    $n+3$, $n^2+3$, cubes, find, perfect
    • Replies: 5
    • Views: 182
    September 25th, 2017, 05:09 Go to last post
  22. Evaluate the product

    Started by lfdahl, September 18th, 2017 17:07
    ;;;, evaluate, n.], product, [lim_nto
    • Replies: 2
    • Views: 134
    September 24th, 2017, 15:10 Go to last post
  23. Evaluate the limit of a trigonometric expression

    Started by lfdahl, September 22nd, 2017 16:53
    arctan, evaluate, sin, tan, x-arctan
    • Replies: 2
    • Views: 136
    September 24th, 2017, 14:21 Go to last post
  24. Determine all real valued differentiable functions ...

    Started by lfdahl, September 22nd, 2017 16:45
    $fx, determine, functions, fxy$, real
    • Replies: 4
    • Views: 153
    September 23rd, 2017, 13:23 Go to last post
  25. Particle trajectory

    Started by lfdahl, September 5th, 2017 16:12
    2 Pages
    1 2
    equation, identify, moves, particle, trajectory
    • Replies: 10
    • Views: 320
    September 20th, 2017, 18:55 Go to last post
  26. Counting Squares Challenge

    Started by lfdahl, September 18th, 2017 16:52
    counting, diagonal, fracn^4-n^212$, grid, squares
    • Replies: 2
    • Views: 117
    September 20th, 2017, 13:58 Go to last post
  27. Number of positive divisors less than 7

    Started by lfdahl, September 16th, 2017 16:10
    $1$, $a$, divisors, number, positive
    • Replies: 2
    • Views: 121
    September 18th, 2017, 14:18 Go to last post
  28. Polynomial in n variables: Prove the identity

    Started by lfdahl, September 10th, 2017 17:09
    $1$, $f$, identity, polynomial, prove
    • Replies: 1
    • Views: 111
    September 15th, 2017, 14:54 Go to last post
  29. Double integral challenge

    Started by lfdahl, September 13th, 2017 16:26
    8y^4+y, double, int, integral, plane
    • Replies: 6
    • Views: 190
    September 15th, 2017, 03:16 Go to last post
  30. Prove the existence of an equilateral triangle

    Started by lfdahl, September 7th, 2017 17:12
    $c$, equilateral, point, prove, triangle
    • Replies: 1
    • Views: 102
    September 12th, 2017, 15:03 Go to last post
  31. find a,b

    Started by Albert, September 10th, 2017 22:24
    1$12^2+39^2+a^2=b^2$, 2$12^2+24^2+a^2=b^2$, bin, find
    • Replies: 2
    • Views: 111
    September 12th, 2017, 02:01 Go to last post

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Top 84 Thread Starters For "Challenge Questions and Puzzles"

RankUser NamePercentage Of TotalThreadsMost Recent Thread
1anemone44.0742Prove (a-b)ᵃ⁻˭...
2Albert21.2358find a,b
3lfdahl5.186Find the maximal value of the ...
4kaliprasad3.559find n
5ZaidAlyafey2.339Harmonic numbers identity
6MarkFL1.831Definite Integral
7Random Variable1.728A residue calculation
8sbhatnagar1.526Two Challenging Integrals
9jacks1.525Indefinite integration involvi...
10DreamWeaver1.424An inverse tangential problem
11caffeinemachine0.915MHB's First Polymath Project.
12Pranav0.813Summation challenge #2
13solakis0.712triangular relations
14Krizalid0.610Continuity of IVP
14Wilmer0.610Tuff Sequence...
14checkittwice0.610Determine all solutions in pos...
15magneto0.59Sequence Challenge
16greg13130.58Trigonometric Product Challeng...
16mathmaniac0.586n^3 + 3 is not a perfect 6th ...
16eddybob1230.58Increasing and Decreasing Numb...
17melese0.47Rational roots
17Rido120.47Find the limit (n!)^(1/n)/n
17hxthanh0.47Write n = a + b + c + ...
17mente oscura0.47Find the 6 reals roots
18CaptainBlack0.46Problem from Paper 3 of the 19...
18Bacterius0.46Divergence of a trigonometric ...
18soroban0.46The Missing intercept
18I like Serena0.46TikZ Challenge 3 - Vector Diag...
18mathbalarka0.46A double sum challenge
18mathworker0.46pigeon hole proof
18Shobhit0.46An Infinite product
18Fallen Angel0.46Find all functions
19Poirot0.35Co-prime challenge
19sadsadsadsa0.35Ricky's Dinner
19jacobi0.35Probability challenge
20Evgeny.Makarov0.24Game on a chessboard
20jakncoke0.24Putnam 2012: A5
20Theia0.24Differentiation challenge
21Also sprach Zarathustra0.23Integral of x^{-x}
21alane19940.23Einstein's Riddle
21Farmtalk0.23Secret Order
21The Lord0.23Integral
21Petrus0.23Differential Equation challeng...
22chisigma0.12A false approach to an integra...
22TheBigBadBen0.12Logic problem
22M R0.12Geometry Challenge
22Fermat0.12integration
22Euge0.12Abstract Algebra Challenge
22Illmatic0.12Sum of reciprocals of roots
22jmprada0.12Sphere diameter
23The Chaz0.11Travelers and coins
23Prove It0.11Challenge: Is cos(pi/60) trans...
23Alexmahone0.11Hourglasses
23tkhunny0.11Missing in NY/PA
23Sherlock0.11Sum involving pi, ln(2) and Ca...
23Fernando Revilla0.11lim x ⌊1 / x⌋ , x...
23HallsofIvy0.11A geometric puzzle
23masters0.11Where's the father?
23DrunkenOldFool0.11infinite sum
23Opalg0.11Puzzle with digits
23Deveno0.11Identify the mystery group
23Amer0.11Nice Puzzle
23princeps0.11LCM Inequality
23Chris110.11Simple, fun puzzle
23QuestForInsight0.11Exponential limit
23topsquark0.11Sort of a challenge
23Petek0.11Unique Factorization Domains
23mssrki0.11Mathematics - a new basis
23johng0.11number of p subgroups
23judytl30.11Factoring over the Integers
23stainburg0.11Boring. Then Prove it!
23jeffer vitola0.11Limit is Sum
23individ0.11Solve triple square Diophantin...
23RLBrown0.11Next integer in this sequence,...
23Bibubo0.11divisibility and sums
23maxkor0.11exactly one triple
23Dai0.11Puzzle
23Prakhar0.11Challenging Integral
23RobJob0.11The connected Game
23Monoxdifly0.11Arrange Mathematical Operation...
23Joppy0.11Show that is the square of an ...
23steevsaul0.11
23bio0.11Year 7 & 8 mathematics puz...
23rick1230.11The Durango Curve Problem
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