Examples of SubSpaces and Non SubSpaces of Polynomial Space

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  • เผยแพร่เมื่อ 15 ก.ย. 2024

ความคิดเห็น • 88

  • @gigglemug247
    @gigglemug247 2 ปีที่แล้ว +2

    It cleared all my doubts ✌️

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      Great..
      Happy to hear that :)

  • @thenewdimension9832
    @thenewdimension9832 2 ปีที่แล้ว +1

    Thankyou so much sir u saved me 💐💐💐💐

  • @Amantheparadise
    @Amantheparadise 11 หลายเดือนก่อน +1

    Very interesting ❤

  • @Rahul.G.Paikaray27
    @Rahul.G.Paikaray27 ปีที่แล้ว +2

    Clear sir 👍👍👍

  • @hafizur12349
    @hafizur12349 2 ปีที่แล้ว +1

    Thank you sir

  • @mathematicalsociety9928
    @mathematicalsociety9928 2 ปีที่แล้ว +1

    sir agr hm x ki power n positive lyn to wo W ko belong krta hy phr wo subspace ho gi

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      Sorry, I didn't get your question.

    • @mathematicalsociety9928
      @mathematicalsociety9928 2 ปีที่แล้ว +1

      sir i am saying that if we let positive x power 4 instead of negitive it will become
      2x power 4 and it belongs to W

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@mathematicalsociety9928 yes correct...
      But then, I am giving counterexample.
      So I have one specific example..
      That is , addition need not always belong to W.

  • @thetechblogger5385
    @thetechblogger5385 2 ปีที่แล้ว +1

    Sir I didn't get one question. The question is ' Let V=P2(R). Then W={a0x^2+a1x+a2 belongs to P2 : a0+a1=0} is the subspace of V or not?

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +2

      It's a subspace..
      Try to prove it..if you get stuck then write down that step, I will check..

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Let u,v belongs to P2 and alpha belongs to R.
      u= a0x^2+a1x+a2
      v= b0x^2+b1x+b2
      For this to be a vector space
      alpha.u +v =(alpha.a0+bo)x^2+(alpha.a1+b1)x + (alpha.a2+b2)
      What to do after this?
      Did I assume everything correct?

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +2

      @@thetechblogger5385 a0+a1=0 and b0+b1=0 so in u+v coefficient of x^2+ coefficient of x = a0+b0+a1+b1=0 . So the condition is satisfied. So u+v is in W.

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Yes Sir u+v is in W but how to prove then scalar multiplication? i.e. alpha.u belongs to W if aplha belongs to R

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@thetechblogger5385 alpha u= alpha*a0+ alpha*a1= alpha*(a0+a1)=alpha*0=0.
      So alpha*u is in w

  • @Shiksha291
    @Shiksha291 2 ปีที่แล้ว +1

    Sir if degree of n greater than equal 1 h to tb ye subspace hoga ya nhi... please reply

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      Nai Hoga..
      F(X)= X AND G(X)= -X.
      Both are of degree 1 but addition is not of degree greater equal 1

    • @Shiksha291
      @Shiksha291 2 ปีที่แล้ว +1

      Okay sir

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@Shiksha291 👍

  • @Learnwithme.07
    @Learnwithme.07 2 ปีที่แล้ว +1

    Is polynomial at most degree 2 a subspace if p’(x) = x?

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +4

      You mean S={ p(x) | deg p(x)

    • @Learnwithme.07
      @Learnwithme.07 2 ปีที่แล้ว +2

      @@DrMathaholic and their addition also then gives 2x
      Thanks a lot for your reply!!!

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +2

      @@Learnwithme.07 yes correct..
      Welcome..

  • @thetechblogger5385
    @thetechblogger5385 2 ปีที่แล้ว +1

    Let V=P2(R). Then which of the following subsets of V are subspace of V.
    i. S1={p belongs to V: p'(1)=0}
    ii. S2= {p belongs to V: p(-1)=1}
    Sir I am confused on how to start this ques.

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +3

      Have you seen 4 and 5th question in the video?
      Same idea..
      (i) is the subspace
      (ii) is not as 0 polynomial does not satisfy the given condition..so (ii) is not a subspace..

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Yes Sir !
      Is this solution correct as well:
      ii.Let p1,p2 belongs to W this implies p1(-1)=p2 (-1)=1
      p=alpha.p1+p2
      p(-1)=alpha.p1(-1)+p2(-1)
      p(-1)= alpha +1
      p(-1) =1 for only alpha=0 and not for all values of alpha belongs to R.
      Therefore it is not a subspace.
      Is this correct as well?

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +3

      @@thetechblogger5385 yes...correct

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Thank you Sir
      You are helping me a lot!

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +3

      @@thetechblogger5385 welcome..

  • @navjotzsingh
    @navjotzsingh ปีที่แล้ว +1

    Sir why 3 degree polynomial is not a vector space ..
    If it is ..then how?
    Plz help me with this doubt

    • @navjotzsingh
      @navjotzsingh ปีที่แล้ว

      Sir plz tell me

    • @DrMathaholic
      @DrMathaholic  ปีที่แล้ว +1

      Degree = 3 can't form a subspace..
      Take p(x)= x^3 and q(x)= -x^3+ x
      Then p +q = x which is a polynomial of degree 1 and not of degree 3.

    • @navjotzsingh
      @navjotzsingh ปีที่แล้ว +1

      @@DrMathaholic sir ..we can do it same for p4 .
      then why p4 is a vector space
      Plz tell..

    • @navjotzsingh
      @navjotzsingh ปีที่แล้ว +1

      @@DrMathaholic plz reply sir

    • @DrMathaholic
      @DrMathaholic  ปีที่แล้ว +1

      @@navjotzsingh P4 is what?
      If you are taking polynomials of degree less equal 4 then yes, it's a subspace.
      But if you are taking equal to 4 then it's not a subspace

  • @lightdevil7143
    @lightdevil7143 2 ปีที่แล้ว +1

    What If U = { f € P/f has rational coefficient} is subspace or not???

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      No..
      Take f from U and pi a real number which is not rational..
      Then pi*f does not belong to U as coefficients are no more rationals...

    • @lightdevil7143
      @lightdevil7143 2 ปีที่แล้ว +1

      @@DrMathaholic ok thank you so much sit it's really mean lots ❤️❤️

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@lightdevil7143 👍😊

    • @lightdevil7143
      @lightdevil7143 2 ปีที่แล้ว +1

      @@DrMathaholic Is S={ (x,y,x)| |x| = |y| =|z| } space of a vector space ? this is not V.S right because When we do -a(x,y,x) is not in S . Is this right

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@lightdevil7143 not because u=(1,-1,1) and v=(1,1,-1) are in S since modulus of each element is 1 but u+v=(2,0,0) and here |2| not equal to |0|

  • @joicet5618
    @joicet5618 2 ปีที่แล้ว +1

    sir can you prove a polynomial with degree >=n

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      please see at 6:45 . There you will see that taking x^{n=1} and - x^{n+1} +1 and adding will give a poly of degree less than n. so its not a subspace

  • @ojosworld2648
    @ojosworld2648 2 ปีที่แล้ว +1

    Sir can you solve this set as a subspace of P
    i.e
    {p€P / degree of p=4 }
    This set is not subspace can you give us example for this plz.

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      X^4 and -x^4+x.
      Addition is not a poly of deg 4

    • @ojosworld2648
      @ojosworld2648 2 ปีที่แล้ว +1

      Thankyou sir

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      @@ojosworld2648 welcome

    • @ojosworld2648
      @ojosworld2648 2 ปีที่แล้ว +1

      Plz.give examples for these also
      1.{p€P / degree of p≤3 }
      Subspace ,yes
      2.{p€P / degree of p≥5}
      Subspace ,no
      3.{p€P / degree of p≤4 and p'(0)=0}
      Don't know?
      4.{p€P / p(1)=0}
      Subspace yes
      Help me with all the questions through examples.

    • @ojosworld2648
      @ojosworld2648 2 ปีที่แล้ว +1

      @@DrMathaholic ??

  • @ankitchowdhury8575
    @ankitchowdhury8575 2 ปีที่แล้ว +1

    How to find dimension of a subspace such that p(x)=p(2x) is satisfied

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      take p(x) = ax+b and use the condition, we get a=0. take p(x) = ax^2+x+c and use the given condition , we get a=0 and b=0. Similarly we always get all coefficients 0 except constant. So p(x) = c. so I think dimension is 1. Do you have the answer key?

    • @ankitchowdhury8575
      @ankitchowdhury8575 2 ปีที่แล้ว +1

      @@DrMathaholic yes sir I got it. I do not have the answer key but your explanation is right. Dim will be 1. Thank you sir ❤️

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +2

      @@ankitchowdhury8575 great..

  • @abhiclassesdu515
    @abhiclassesdu515 ปีที่แล้ว +1

    ❤❤

  • @thetechblogger5385
    @thetechblogger5385 2 ปีที่แล้ว +1

    Sir please suggest a way to prepare theorems?
    Sir can you prepare a lec on Span of Subset?

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +2

      Hi,
      Yes, I want to make but occupied with college work..hopefully soon.
      Regarding theorems, just try to understand the meaning and make sure step by step proof is clear..
      Any queries then you can ask here.

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Ok Sir
      Thank you so much Sir! :)

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +3

      @@thetechblogger5385 welcome

    • @DrMathaholic
      @DrMathaholic  2 ปีที่แล้ว +1

      Have you seen this lecture on span??
      th-cam.com/video/cui5yxBWpkQ/w-d-xo.html

    • @thetechblogger5385
      @thetechblogger5385 2 ปีที่แล้ว +1

      @@DrMathaholic Sir can you please explain the proof of the theorem "If S is a non-empty subset of a vector space V, then [S] is the smallest subspace of V containing S."