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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: 1,961
    October 15th, 2017, 16:11 Go to last post
  1. Normal Thread Normal Threads

  2. Weird function challenge

    Started by castor28, January 16th, 2018 05:03
    2 Pages
    1 2
    $mathbbr$, discontinuous, function, interval, sense
    • Replies: 10
    • Views: 167
    Today, 12:27 Go to last post
  3. Sum to product inequalities

    Started by lfdahl, January 15th, 2018 17:26
    $1-alpha_11-alpha_2, 1-alpha_n, geq, implies, sum
    • Replies: 3
    • Views: 102
    Yesterday, 19:10 Go to last post
  4. Determine the integer with 3 specific properties

    Started by lfdahl, January 12th, 2018 16:56
    $n$, determine, digits, integer, properties
    • Replies: 7
    • Views: 146
    January 15th, 2018, 14:41 Go to last post
  5. Liars and truthtellers

    Started by castor28, January 4th, 2018 05:23
    inhabitants, island, knaves, number, yes-no
    • Replies: 1
    • Views: 87
    January 14th, 2018, 05:06 Go to last post
    • Replies: 2
    • Views: 83
    January 13th, 2018, 14:58 Go to last post
  6. Find the smallest A satisfying the inequality

    Started by lfdahl, January 11th, 2018 14:46
    find, number, real, satisfying, smallest
    • Replies: 3
    • Views: 107
    January 13th, 2018, 00:53 Go to last post
  7. Sum of squared cosines is in fact independent of ...

    Started by lfdahl, January 9th, 2018 15:14
    cube, denote, independent, sphere, ^2angle
    • Replies: 2
    • Views: 110
    January 11th, 2018, 14:34 Go to last post
  8. Prove the nested radicals identity

    Started by lfdahl, January 9th, 2018 18:24
    identity, nested, prove, sqrtn+sqrtn-, [sqrtn
    • Replies: 4
    • Views: 117
    January 10th, 2018, 15:25 Go to last post
  9. Find the maximal value of the sum

    Started by lfdahl, October 8th, 2017 14:36
    find, maximal, numbers, real, satisfying
    • Replies: 4
    • Views: 192
    January 9th, 2018, 05:27 Go to last post
  10. Find the maximal number of subsets, k.

    Started by lfdahl, January 1st, 2018 15:04
    $a_i, find, leq, maximal, subsets
    • Replies: 1
    • Views: 77
    January 7th, 2018, 14:30 Go to last post
  11. Evaluate the integral

    Started by lfdahl, January 1st, 2018 15:16
    cdot, cos, evaluate, integral, [int_0^2picos
    • Replies: 9
    • Views: 300
    January 7th, 2018, 14:17 Go to last post
  12. [SOLVED] Polynomial challenge

    Started by castor28, December 21st, 2017 05:39
    $fr=p$, $q$, $r$, integers, polynomial
    • Replies: 3
    • Views: 146
    January 2nd, 2018, 00:24 Go to last post
  13. Upper and lower bounds of a binary number

    Started by lfdahl, December 29th, 2017 12:55
    $9$, digits, lower, number, upper
    • Replies: 4
    • Views: 97
    December 30th, 2017, 16:08 Go to last post
  14. 2 x 2 matrix puzzle

    Started by lfdahl, December 29th, 2017 12:38
    beginpmatrix, endpmatrix], integer, matrix, [s^n=
    • Replies: 4
    • Views: 101
    December 29th, 2017, 18:09 Go to last post
  15. Sum of polynomial coefficients inequality to be proved

    Started by lfdahl, December 29th, 2017 12:29
    $pqx$, $qx, polynomial, real, sum
    • Replies: 2
    • Views: 67
    December 29th, 2017, 17:55 Go to last post
  16. high school geometry

    Started by solakis, December 26th, 2017 19:56
    circle, examination, geometry, high, school
    • Replies: 2
    • Views: 91
    December 27th, 2017, 05:00 Go to last post
  17. Trigonometric sum identity

    Started by lfdahl, December 16th, 2017 16:21
    identity, prove, sum, trigonometric, [sum_j=1^n-1csc^2left
    • Replies: 2
    • Views: 140
    December 22nd, 2017, 16:16 Go to last post
  18. Definite integral challenge

    Started by lfdahl, December 17th, 2017 18:19
    $$int_0^piln, challenge, definite, integral, prove
    • Replies: 2
    • Views: 110
    December 18th, 2017, 15:27 Go to last post
  19. A finite set of integers

    Started by lfdahl, December 14th, 2017 04:52
    $a^2b^2$, $t$, finite, prove, set
    • Replies: 2
    • Views: 78
    December 15th, 2017, 07:01 Go to last post
  20. Show, that a is an integer

    Started by lfdahl, December 12th, 2017 11:35
    calculator, integer, show, sqrt[3]7+5sqrt2, sqrt[3]7-5sqrt2$
    • Replies: 3
    • Views: 114
    December 13th, 2017, 07:56 Go to last post
  21. Not all the roots are real

    Started by lfdahl, December 12th, 2017 11:10
    $a_1^2, a_2$, real, roots, show
    • Replies: 2
    • Views: 73
    December 12th, 2017, 17:38 Go to last post
  22. Complex roots challenge

    Started by lfdahl, December 1st, 2017 15:56
    $x^7-7=, complex, equation, prod_1leq, roots
    • Replies: 1
    • Views: 109
    December 9th, 2017, 16:57 Go to last post
  23. high school geometry

    Started by solakis, December 7th, 2017 21:57
    abc, ba=c, bc=a, bd=b, bisector
    • Replies: 0
    • Views: 55
    December 7th, 2017, 21:57 Go to last post
  24. Find all functions satisfying ...

    Started by lfdahl, November 30th, 2017 15:52
    find, functions, mathbbn$, mathbbnrightarrow, satisfying
    • Replies: 5
    • Views: 136
    December 7th, 2017, 14:40 Go to last post
  25. divisible by 7

    Started by kaliprasad, December 7th, 2017 00:04
    divisible, integer, product, show
    • Replies: 1
    • Views: 68
    December 7th, 2017, 06:04 Go to last post
  26. Unsolved Challenge
    Show ⌊aš⁷⁸⁸⌋ and ⌊aš⁹⁸⁸⌋ are both divisible by 17

    Started by anemone, December 4th, 2017 11:08
    $x^3−, 3x^2+, divisible, equation, show
    • Replies: 1
    • Views: 92
    December 5th, 2017, 04:53 Go to last post
  27. Unsolved Challenge
    Logarithmic inequality

    Started by anemone, December 3rd, 2017 07:58
    $log_a, logarithmic, log_b+1, log_c+2, log_d+3
    • Replies: 0
    • Views: 87
    December 3rd, 2017, 07:58 Go to last post
  28. Find the greatest real number T

    Started by lfdahl, November 29th, 2017 16:54
    $x$, $y+z, find, greatest, number
    • Replies: 2
    • Views: 102
    November 30th, 2017, 15:37 Go to last post
  29. Calculus inequality challenge

    Started by lfdahl, November 28th, 2017 17:58
    calculus, geq, prove, satisfies, [int_0^1fracfxfx+frac12dx
    • Replies: 2
    • Views: 90
    November 29th, 2017, 16:57 Go to last post

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Top 84 Thread Starters For "Challenge Questions and Puzzles"

RankUser NamePercentage Of TotalThreadsMost Recent Thread
1anemone43.3747Show ⌊aš⁷⁸&#...
2Albert20.7358find a,b
3lfdahl6.7115Sum to product inequalities
4kaliprasad3.560divisible by 7
5ZaidAlyafey2.339Harmonic numbers identity
6MarkFL1.831Definite Integral
7Random Variable1.628A residue calculation
8sbhatnagar1.526Two Challenging Integrals
9jacks1.425Indefinite integration involvi...
10DreamWeaver1.424An inverse tangential problem
11caffeinemachine0.915MHB's First Polymath Project.
12solakis0.814high school geometry
13Pranav0.813Summation challenge #2
14Krizalid0.610Continuity of IVP
14Wilmer0.610Tuff Sequence...
14checkittwice0.610Determine all solutions in pos...
15greg13130.59Trigonometric Sum
15magneto0.59Sequence Challenge
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
18CaptainBlack0.36Problem from Paper 3 of the 19...
18Bacterius0.36Divergence of a trigonometric ...
18soroban0.36The Missing intercept
18I like Serena0.36TikZ Challenge 3 - Vector Diag...
18mathbalarka0.36A double sum challenge
18mathworker0.36pigeon hole proof
18Shobhit0.36An Infinite product
18Fallen Angel0.36Find 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...
21castor280.23Weird function challenge
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 ...
23bio0.11Year 7 & 8 mathematics puz...
23rick1230.11The Durango Curve Problem
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