An Ingenious Solution Strategy! [ Putnam 2018 A1 ]

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  • Опубліковано 19 гру 2024

КОМЕНТАРІ • 128

  • @NPCooking69
    @NPCooking69 4 роки тому +19

    *Over on my Channel you can find the Outtake ( **ua-cam.com/video/mfaSDC4eIog/v-deo.html** ) as well as my first attempt, the Alternative Solution! **ua-cam.com/video/uaFZ69NLRBU/v-deo.html*
    Make sure to support the channel by watching all the relevant videos and to consider subscribing to Flammy 2 if you haven't done so already! =)

  • @AndrewDotsonvideos
    @AndrewDotsonvideos 4 роки тому +70

    Worst "how to peel a boiled egg" video I've ever seen. You don't even look good peeling the egg. Come to think of it, I don't think you followed the celebrated 13 step process of egg peeling. What has happened to UA-cam!?

  • @palmenros
    @palmenros 4 роки тому +40

    I always messed up the “and” and “or” symbols, but here is a little trick I have learned to remember them: the “and” symbol is like an A for “and”. It sounds stupid, but for me it works very well

    • @PapaFlammy69
      @PapaFlammy69  4 роки тому +39

      problem is the german "und" ^^'

    • @LuisAForero295
      @LuisAForero295 4 роки тому +6

      I did the relationship with Union and Intersection when you work with inequalities.
      x > 3 ∧ x < 5 → x > 3 ⋂ x < 5
      x > 1 ∨ x > 3 → x > 1 ⋃ x > 3

    • @josephedwards7198
      @josephedwards7198 4 роки тому +2

      @Flamable Maths I think of it as like a pointy n in “and” (and “und”). Like fish ‘n’ chips.

    • @aasyjepale5210
      @aasyjepale5210 4 роки тому +1

      I think that when water is poured on top of "and", the water will flow on both sides, and for "or", the symbol will fall on one side and the water flows on that side only or maybe the symbol doesnt fall and the water, again, flows on both sides!

    • @Kaphas1
      @Kaphas1 4 роки тому +1

      The “or” symbol comes originally from the Latin “vel”(same way that the & symbol comes from a stylised “et”). Makes it easy for me to remember.

  • @kumarkrish1073
    @kumarkrish1073 4 роки тому +25

    Ur patience level is ultimate in this question ✌

    • @TechToppers
      @TechToppers 4 роки тому +1

      Nope! I won't say that. I'm ready to do any calculation if I get an Olympiad problem correct.

  • @aarryasaraf
    @aarryasaraf 4 роки тому +33

    There's the 145 iq papa flammy

  • @skylardeslypere9909
    @skylardeslypere9909 4 роки тому +2

    17:47 also all the solutions where a and b are switched :)

  • @rcnayak_58
    @rcnayak_58 4 роки тому +1

    My earlier solution was a specific specific solution. There can be innumerable solution sets to the problem if we consider real values for a and b. The general solution values for a = (1/2)*[ 3 * k + sqrt( 9 * k^2 - 8072 * k)] and b = (1/2)*[ 3 * k - sqrt( 9 * k^2 - 8072 * k)] for any value of k greater than 897.

  • @Ajolago1
    @Ajolago1 4 роки тому +1

    a = infinity, b = (3/2018)^-1, nailed it

  • @eliyasne9695
    @eliyasne9695 4 роки тому +1

    13:25
    Everything makes sense if you think about it *hard enough* .

  • @JAY-oi1vy
    @JAY-oi1vy Рік тому

    Sir, alternatively, u could have done, taking 1/b to RHS once then cross multiply,
    We get 2018b = (3b - 2018)a
    Similarly with 1/a,
    2018a = (3a - 2018)b
    On multiplying those 2 eqn, we get 2018² = (3a - 2018)(3b - 2018)
    N rest as u solved!

  • @VaradMahashabde
    @VaradMahashabde 4 роки тому +9

    Why didn't you just check the modulus by 3?
    Each factor on RHS (3a-2018,3b-2018) is 1 mod 3, while the only "prime factors mod 3" (factors which are 1 mod 3 themselves but any subfactors are not) of 2018^2 on the LHS is 4*1009^2, so since we have to distribute 3 possible "prime factors" between a and b, 2^3 or 8 solutions exist

  • @billdrish8818
    @billdrish8818 4 роки тому +2

    If I may say so, you are a great math teacher!

  • @misko933
    @misko933 4 роки тому +2

    Pretty cool solution, thank ou for sharing this fellow mathematician :)!

  • @joshuamason2227
    @joshuamason2227 4 роки тому +1

    8:28 I have no idea what's going on but I'm just pleased that he's happy

  • @mctrafik
    @mctrafik 3 роки тому

    Thumbs up for explaining why some of the solutions are eliminated!

  • @ElchiKing
    @ElchiKing 4 роки тому +4

    You know, this would be much easier, if you simply write a=c*x, b=d*x where x=gcd(a,b) (positive). Then c,d are coprime.
    1/a+1/b=3/2018 is (by rearranging) equivalent to (2018-3b)a=-2018b, so a| 2018b and by symmetry b|2018a.
    Hence, cx|2018dx and dx|2018cx. Dividing by x and remembering that c and d are coprime yields c|2018 and d|2018.
    So, c and d can both only be in the set {-2018,-1009,-2,-1,1,2,1009,2018}.
    On the other hand, 1/a+1/b=(c+d)/(cd x)=3/2018, so 3|c+d and as soon as we have c,d, we can simply solve for x by rearranging to
    x=2018(c+d)/(3cd) [note that since c,d|2018 and gcd(c,d)=1, we get cd|2018, so this is an integer iff 3|c+d]
    W.l.o.g, we can say |c|0 we have c>0. Taking into account that c and d are coprime, we have the following pairs (c,d) left to check:
    (1,-2018): Impossible, since -2017 is not divisible by 3
    (1,-1009): possible, since -1008 is divisible by 3 and indeed, with x=2*1008/3=336*2, hence a=336*2, b=-336*2*1009, we get 1/a+1/b=3/2018
    (1,-2) impossible, since -1 is not divisible by 3
    (1,-1) obviously here 1/a+1/b=0 regardless of x
    (1,1) not divisible by 3
    (1,2) possible and x=1009 yields a=1009, b=2018 and 1/a+1/b=3/2018
    (1,1009) not divisible by 3
    (1,2018) possible and x=673 yields a=673, b=673*2018
    (2,-1009) not divisible by 3
    (2,1009) possible with x=337, a=674, b=1009*337
    (for bigger c there is no possible d)
    So, all solutions are the following:
    (336*2,-336*2*1009), (1009,2018),(673,673*2018),(674,1009*337), (-336*2018,336*2),(2018,1009),(673*2018,673),(1009*337,674)
    (Note that this method works for all problems of the form 1/a+1/b=y/z with y/z in lowest terms if the prime factorization of y and z is known:
    we always get y|c+d and c|z, d|z)

    • @ElchiKing
      @ElchiKing 4 роки тому +1

      In fact, the method works for all problems of the form k/a+l/b=y/z with given integers k,l,y,z (y,z in lowest terms, k and l not equal to 0)

  • @vikaskalsariya9425
    @vikaskalsariya9425 4 роки тому +16

    MIchael Penn also has a great solution of this

    • @vikaskalsariya9425
      @vikaskalsariya9425 4 роки тому +5

      @@avisingh0009 I think the solution of Michael is very less time comsuming and good for learning new tricks too. While this video is rather aimed at a more general public, Michael prefers to use some good tools which are very helpful.

    • @vikranttyagiRN
      @vikranttyagiRN 4 роки тому +1

      Link?

    • @vikaskalsariya9425
      @vikaskalsariya9425 4 роки тому +2

      @@vikranttyagiRN ua-cam.com/video/2bB_Ec0jmCI/v-deo.html here bro.

    • @vikranttyagiRN
      @vikranttyagiRN 4 роки тому +1

      @@vikaskalsariya9425 thanks

  • @JoeDan54
    @JoeDan54 4 роки тому +21

    Yoooo I remember this problem

  • @nnniv
    @nnniv 4 роки тому +10

    ah finally something my smol brain can easily understand

  • @deveshsharma8118
    @deveshsharma8118 4 роки тому

    This is indeed a genious method...this video is one of the best of urs🙌🙌

  • @naseemveevers3619
    @naseemveevers3619 4 роки тому +11

    i guess you could say this is 🆎rilliant question

  • @raffaelevalente7811
    @raffaelevalente7811 3 роки тому

    I did the simplification multiplying both sides by 2018 ab and then by 3.
    Then added 2018^2 to both sides to get
    (3a - 2018)(3b - 2018) = 2018^2 = 2^2 1009^2
    and solved all cases where for instance
    3 a-2018=1,3 b-2018=2018^2
    which gives (673, 1358114)
    3 a-2018=2,3 b-2018=2 1009^2
    and so on, getting 8 solutions
    (-678048,672),
    (672,-678048),
    (673,1358114),
    (674,340033),
    (1009,2018),
    (2018,1009),
    (340033,674),
    (1358114,673)

  • @Xammed
    @Xammed 4 роки тому

    I took the exam that year! Yes!

  • @pavelievlev9730
    @pavelievlev9730 3 роки тому

    what you proved here is a nice relation between the geometric mean GM(a,b) = sqrt(ab) and the harmonic mean HM(a,b) = 2/(1/a + 1/b)

  • @kpt123456
    @kpt123456 2 роки тому

    nice solution.teaches a new method

  • @mach2570
    @mach2570 4 роки тому

    I don't get why you took such a roundabout approach to get to the factorization at 9:45, It can be directly written by observation from the original equation.

  • @kekskuh4108
    @kekskuh4108 4 роки тому +3

    Where did you get that clock from?

    • @PapaFlammy69
      @PapaFlammy69  4 роки тому

      It's an exclusive for my channel. Only available till tomorrow ^^ teespring.com/flammable-math-clock

    • @kekskuh4108
      @kekskuh4108 4 роки тому +1

      @@PapaFlammy69 Phew so good thing I looked today

    • @PapaFlammy69
      @PapaFlammy69  4 роки тому

      Definitely! :D

  • @junerichardson3377
    @junerichardson3377 2 роки тому

    If you know Simon's Favorite Factoring Trick, you can skip the video to 9:14

  • @hamsterdam1942
    @hamsterdam1942 4 роки тому +1

    13:00 it was around 12 minutes long

  • @meetjoshi9853
    @meetjoshi9853 4 роки тому +12

    9^2 views in 9 minutes 😳

  • @BrianAmedee
    @BrianAmedee 4 роки тому +1

    I remember this question, I got it wrong lol. Thanks Flamma pappy you thicc boi :)

  • @harrypotter5460
    @harrypotter5460 4 роки тому

    I remember solving this one a couple years ago. I can’t remember exactly what method I used but it definitely wasn’t this nice.

  • @greg73049
    @greg73049 4 роки тому

    what is the intro music called?

  • @cuonghienthaosonbuitrung2841
    @cuonghienthaosonbuitrung2841 4 роки тому

    Putnam 2018 A1: Flammable Maths vs Micheal Penn
    See his video:ua-cam.com/video/2bB_Ec0jmCI/v-deo.html

  • @edwardhudson815
    @edwardhudson815 Рік тому

    What is ZxZ

  • @rome8726
    @rome8726 4 роки тому

    So smart.😮

  • @mathadventuress
    @mathadventuress 4 роки тому

    Michael Penn did this problem already. Are you doing a different method

    • @chhabisarkar9057
      @chhabisarkar9057 4 роки тому +3

      Bois don't copy methods

    • @Kdd160
      @Kdd160 4 роки тому

      @@chhabisarkar9057 haha nice one

  • @shahriarrudra7495
    @shahriarrudra7495 4 роки тому

    What is the definition of problem...

  • @PSNsomeonealive
    @PSNsomeonealive 4 роки тому

    MM very good papa thank you

  • @chronicsnail6675
    @chronicsnail6675 4 роки тому +1

    just use python? i mean the math approach booil down to computation so why not just use python

  • @tsunningwah3471
    @tsunningwah3471 4 роки тому

    Love from 🇭🇰

  • @ChandrasegaranNarasimhan
    @ChandrasegaranNarasimhan 7 місяців тому

    Physicist to mathematician: Why do you have to call it commutative? You can say I have 2 equations and I am multiplying them together. I understood the symmetry part. If you ask me I would write a program for all integers. It seems like you have found a better way. Checking for multiples of 3. That move got me. I did not think about that. Thanks. Hmmmm.

  • @hnnagarathna7286
    @hnnagarathna7286 4 роки тому +6

    Good evening fellow mathematicians coz it's 630 pm in India
    Hello smart PPL

  • @TechToppers
    @TechToppers 4 роки тому +2

    Believe me or not...
    The similar problem was given to 5th and 6th graders in India (age (10-12)). The name of examination was NMTC (Gauss Contest) Level 2. The main point was... The calculation was lot easier... It was 1/m + 1/n = 3/17.
    This was the problem. Can you imagine?
    Btw, I found a direct formula for these questions. For 1/x + 1/y = 1/a
    (x-a)(y-a)= a²
    Later you're smart...

  • @XxS4NN4SxX
    @XxS4NN4SxX 4 роки тому

    This might be this first one I get to solve lol (except for the fact that I only read the thumbnail and looked for positive a and b, thus missing one solution)

  • @pyLz
    @pyLz 4 роки тому

    wtf, this is actually amazing no baiteroni

  • @giannisr.7733
    @giannisr.7733 4 роки тому

    0:13 Competitive *_METH_* problems

  • @masterlaughter4924
    @masterlaughter4924 4 роки тому +2

    I could not figure this out...): looks like pappa has to hold my hand and walk me through the problem once again):

  • @hamsterdam1942
    @hamsterdam1942 4 роки тому +1

    notation 3a = 2019 AND 2017 freaked me out

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому +3

    When you don´t know what to comment and you just comment I don´t know what to comment

  • @sadchicken5282
    @sadchicken5282 4 роки тому +1

    Something is wrong with this video but i can’t get it

  • @squibble311
    @squibble311 3 роки тому

    this comment was made before watching:
    is the solution b=2018 a=1009
    _oh you need to find all ordered pairs_

  • @torment808
    @torment808 4 роки тому

    no one:
    me: how the fuck was this video released one hour ago and the top comment from flammable maths 2 is two days old?

  • @ricardoparada5375
    @ricardoparada5375 4 роки тому

    Damn I would not find this solution out in time lmao

  • @juliust8429
    @juliust8429 Рік тому

    You made an error in the way you copied the question, the question is not taking place in Z x Z, rather N x N. Copied directly from the exam it says "Find all ordered pairs (a,b) of *positive integers* for which...", i.e., you should not be considering values of a or b that are less than 0.

  • @javacuber-c5j
    @javacuber-c5j 4 роки тому +3

    Easy solution „und“ is „unten“ open and „oder“ is „oben“ open. Isn’t German a beautiful language.

    • @PapaFlammy69
      @PapaFlammy69  4 роки тому +1

      The u in und is the killer for me here, since u looks like ∨ lel

  • @prashantbhatta6680
    @prashantbhatta6680 4 роки тому

    can someone tell me how cos(x)=1 in the clock?

    • @Kdd160
      @Kdd160 4 роки тому +5

      By the fundamental theorem of engineering lmao

  • @aleksandervadla4840
    @aleksandervadla4840 4 роки тому

    Michael penna video was also real guuci

  • @tszhanglau5747
    @tszhanglau5747 4 роки тому +1

    I am having a deja vu...

    • @PapaFlammy69
      @PapaFlammy69  4 роки тому

      Why?

    • @maheshpatel7691
      @maheshpatel7691 4 роки тому +3

      @@PapaFlammy69 How can a student do that in exam!! Btw, how much time is given per question?

    • @tszhanglau5747
      @tszhanglau5747 4 роки тому

      @@PapaFlammy69 I have seen the question on a thumbnail of another video. Forgot which,but not yours. Didn't watch said video though.

  • @gcewing
    @gcewing 4 роки тому

    a before b, except after... no, wait, that's something else.

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    Whoa. so cool!

  • @remlatzargonix1329
    @remlatzargonix1329 4 роки тому

    Question: What happened to my 3000 apples?

    • @aasyjepale5210
      @aasyjepale5210 4 роки тому

      Nothing. If you have 3000 apples and you dont substract any apples, then you have 3000 apples.

  • @_mishi
    @_mishi 4 роки тому

    Bruh, UA-cam is so broken that it's showing me that this video has 30,624,950 views like wha?

    • @carlosdecabodelavega3660
      @carlosdecabodelavega3660 4 роки тому

      It must be that you were watching a video with those views and then went here and the video was still loadig so you have the views of the previous ideo you were watching

  • @ogorangeduck
    @ogorangeduck 4 роки тому

    use the gOUgU tHeOReM

  • @MathIguess
    @MathIguess 4 роки тому +1

    Arithmethicc xD lol

  • @geniusgamer8046
    @geniusgamer8046 3 роки тому +1

    u were criticizing India's education system for giving Arithematic mean & geometric mean problems hidden in Algebra questions. but I feel this to b more stupid to get through long calculations rather than linking different areas in maths together.

  • @schneider.mariane
    @schneider.mariane 4 роки тому

    ??? a=1009, b=2018, what is the problem? What is the video about? I do not watch it, the solution is trivial.

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    nice intro.

  • @user-en5vj6vr2u
    @user-en5vj6vr2u 4 роки тому

    I’m so early that papa hasn’t hearted all the comments yet

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    You had this video unlisted before Niw you un(un listed it)

    • @caesar_cipher
      @caesar_cipher 4 роки тому

      Why do you post so much garbage comments on every video ? I really like reading comment section for additional insights and u spoil it for many like us. Its ok to have some fun but have some respect for the forum

    • @carlosdecabodelavega3660
      @carlosdecabodelavega3660 4 роки тому

      @@caesar_cipher >:(

  • @AdityaKumar-ij5ok
    @AdityaKumar-ij5ok 4 роки тому

    arethmethicc phew...

  • @Noscope-wg3dt
    @Noscope-wg3dt 4 роки тому

    Smort

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому +1

    9^2 views in 9 minutes
    9 views per minute in the first 9 minutes

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    Only 81 views i don´t get it

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    81 views it´s Frozen

  • @akjakj5200
    @akjakj5200 4 роки тому

    3ab-2018a-2018b=0 -> 9ab-3*2018a-3*2018b=0 --> (3a-2018)(3b-2018)=(2018)^2 .....

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    Eat Joshi

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    666 views

    • @Kdd160
      @Kdd160 4 роки тому

      No, actually the views are 6969 views which is OBVIOUSLY my fav no.

    • @carlosdecabodelavega3660
      @carlosdecabodelavega3660 4 роки тому

      @@Kdd160 Why?

    • @Kdd160
      @Kdd160 4 роки тому

      @@carlosdecabodelavega3660 :))

    • @carlosdecabodelavega3660
      @carlosdecabodelavega3660 4 роки тому

      @@Kdd160 I guess you saw my video on the proof that a negative times a negative is a positive right?

    • @Kdd160
      @Kdd160 4 роки тому

      @@carlosdecabodelavega3660 sorry I did not see it yet I am watching it now

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    This video is mathematically CuRSeD

  • @carlosdecabodelavega3660
    @carlosdecabodelavega3660 4 роки тому

    The first dislike

    • @rathipatla
      @rathipatla Рік тому

      bro just made sfft so much harder than it had to be