Quadratic Equations - Proof of Common Root [on hold]

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Prove that the equations (q-r)x^2 + (r-p)x + p-q = 0 and (r-p)x^2 + (p-q)x + q-r = 0 have a common root.







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put on hold as off-topic by amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus Aug 3 at 20:55


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus
If this question can be reworded to fit the rules in the help center, please edit the question.








  • 4




    Add some of your thoughts, what have you tried so far?
    – zzuussee
    Aug 3 at 18:30







  • 1




    @GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
    – amWhy
    Aug 3 at 18:33











  • @amWhy Ok, sorry, should I rollback? I assumed looking at the title
    – GoodDeeds
    Aug 3 at 18:33











  • @GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
    – amWhy
    Aug 3 at 18:34







  • 3




    Plug in $x=1$ and see what happens.
    – Anurag A
    Aug 3 at 18:38














up vote
-2
down vote

favorite
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Prove that the equations (q-r)x^2 + (r-p)x + p-q = 0 and (r-p)x^2 + (p-q)x + q-r = 0 have a common root.







share|cite|improve this question













put on hold as off-topic by amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus Aug 3 at 20:55


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus
If this question can be reworded to fit the rules in the help center, please edit the question.








  • 4




    Add some of your thoughts, what have you tried so far?
    – zzuussee
    Aug 3 at 18:30







  • 1




    @GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
    – amWhy
    Aug 3 at 18:33











  • @amWhy Ok, sorry, should I rollback? I assumed looking at the title
    – GoodDeeds
    Aug 3 at 18:33











  • @GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
    – amWhy
    Aug 3 at 18:34







  • 3




    Plug in $x=1$ and see what happens.
    – Anurag A
    Aug 3 at 18:38












up vote
-2
down vote

favorite
2









up vote
-2
down vote

favorite
2






2





Prove that the equations (q-r)x^2 + (r-p)x + p-q = 0 and (r-p)x^2 + (p-q)x + q-r = 0 have a common root.







share|cite|improve this question













Prove that the equations (q-r)x^2 + (r-p)x + p-q = 0 and (r-p)x^2 + (p-q)x + q-r = 0 have a common root.









share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Aug 3 at 20:30
























asked Aug 3 at 18:28









Gaurav Choudhury

62




62




put on hold as off-topic by amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus Aug 3 at 20:55


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus
If this question can be reworded to fit the rules in the help center, please edit the question.




put on hold as off-topic by amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus Aug 3 at 20:55


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, John Ma, Mike Miller, Xander Henderson, Leucippus
If this question can be reworded to fit the rules in the help center, please edit the question.







  • 4




    Add some of your thoughts, what have you tried so far?
    – zzuussee
    Aug 3 at 18:30







  • 1




    @GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
    – amWhy
    Aug 3 at 18:33











  • @amWhy Ok, sorry, should I rollback? I assumed looking at the title
    – GoodDeeds
    Aug 3 at 18:33











  • @GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
    – amWhy
    Aug 3 at 18:34







  • 3




    Plug in $x=1$ and see what happens.
    – Anurag A
    Aug 3 at 18:38












  • 4




    Add some of your thoughts, what have you tried so far?
    – zzuussee
    Aug 3 at 18:30







  • 1




    @GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
    – amWhy
    Aug 3 at 18:33











  • @amWhy Ok, sorry, should I rollback? I assumed looking at the title
    – GoodDeeds
    Aug 3 at 18:33











  • @GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
    – amWhy
    Aug 3 at 18:34







  • 3




    Plug in $x=1$ and see what happens.
    – Anurag A
    Aug 3 at 18:38







4




4




Add some of your thoughts, what have you tried so far?
– zzuussee
Aug 3 at 18:30





Add some of your thoughts, what have you tried so far?
– zzuussee
Aug 3 at 18:30





1




1




@GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
– amWhy
Aug 3 at 18:33





@GoodDeeds I think you assumed x*2* = $x^2,$ etc. Let's ask the asker, first and foremost, before assuming we know what they are asking and editing (with the possibility of having changed the question entirely).
– amWhy
Aug 3 at 18:33













@amWhy Ok, sorry, should I rollback? I assumed looking at the title
– GoodDeeds
Aug 3 at 18:33





@amWhy Ok, sorry, should I rollback? I assumed looking at the title
– GoodDeeds
Aug 3 at 18:33













@GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
– amWhy
Aug 3 at 18:34





@GoodDeeds: No, let's just ask Gaurav if the edited question is what they intended to ask. If they fail to respond yes or no, we'll just leave the question as you formatted it.
– amWhy
Aug 3 at 18:34





3




3




Plug in $x=1$ and see what happens.
– Anurag A
Aug 3 at 18:38




Plug in $x=1$ and see what happens.
– Anurag A
Aug 3 at 18:38










2 Answers
2






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0
down vote













Hint: Computing the roots, we get



$$x_1=1,x_2=fracp-qq-r,x_3=1,x_4=fracr-qp-r$$






share|cite|improve this answer





















  • What happens if $q=r$?
    – Michael Rozenberg
    Aug 3 at 19:04






  • 1




    If $q=r$ we get no quadratic equation.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:07










  • Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
    – Dr. Sonnhard Graubner
    Aug 3 at 19:11










  • I think it's enough $x=1$.
    – Michael Rozenberg
    Aug 3 at 19:12










  • Ok, so i will sleep better Michael.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:18

















up vote
0
down vote













Consider the polinomial of degree 2 vector space. Let $a in mathbbR$ such as $(q - r, r - p, p - q) = a(r - p, p - q, q - r) iff begincases
q - r - ar + ap = 0\
r - p -ap + aq = 0\
p - q -aq + ar = 0
endcases
$. Then
$left(beginarrayccc
a & 1 & -1-a\
-1-a & a & 1\
1 & -1-a & a
endarrayright)left(beginarrayccc
p\
q\
r
endarrayright) = left(beginarrayccc
0\
0\
0
endarrayright)$ and $left|beginarrayccc
a & 1 & -1-a\
-1-a & a & 1\
1 & -1-a & a
endarrayright| = 0$
Hence,the set $S = (q - r)x^2 + (r - p)x + p - q, (r - p)x^2 + (p - q)x + (q - r)$ is linear dependent. The dimension of space generated by $S$ is least equal 1 and the kernel dimension is great or equal 2. Hence, the equation system are at least one common solution.






share|cite|improve this answer






























    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    0
    down vote













    Hint: Computing the roots, we get



    $$x_1=1,x_2=fracp-qq-r,x_3=1,x_4=fracr-qp-r$$






    share|cite|improve this answer





















    • What happens if $q=r$?
      – Michael Rozenberg
      Aug 3 at 19:04






    • 1




      If $q=r$ we get no quadratic equation.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:07










    • Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
      – Dr. Sonnhard Graubner
      Aug 3 at 19:11










    • I think it's enough $x=1$.
      – Michael Rozenberg
      Aug 3 at 19:12










    • Ok, so i will sleep better Michael.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:18














    up vote
    0
    down vote













    Hint: Computing the roots, we get



    $$x_1=1,x_2=fracp-qq-r,x_3=1,x_4=fracr-qp-r$$






    share|cite|improve this answer





















    • What happens if $q=r$?
      – Michael Rozenberg
      Aug 3 at 19:04






    • 1




      If $q=r$ we get no quadratic equation.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:07










    • Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
      – Dr. Sonnhard Graubner
      Aug 3 at 19:11










    • I think it's enough $x=1$.
      – Michael Rozenberg
      Aug 3 at 19:12










    • Ok, so i will sleep better Michael.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:18












    up vote
    0
    down vote










    up vote
    0
    down vote









    Hint: Computing the roots, we get



    $$x_1=1,x_2=fracp-qq-r,x_3=1,x_4=fracr-qp-r$$






    share|cite|improve this answer













    Hint: Computing the roots, we get



    $$x_1=1,x_2=fracp-qq-r,x_3=1,x_4=fracr-qp-r$$







    share|cite|improve this answer













    share|cite|improve this answer



    share|cite|improve this answer











    answered Aug 3 at 18:52









    Dr. Sonnhard Graubner

    66.6k32659




    66.6k32659











    • What happens if $q=r$?
      – Michael Rozenberg
      Aug 3 at 19:04






    • 1




      If $q=r$ we get no quadratic equation.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:07










    • Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
      – Dr. Sonnhard Graubner
      Aug 3 at 19:11










    • I think it's enough $x=1$.
      – Michael Rozenberg
      Aug 3 at 19:12










    • Ok, so i will sleep better Michael.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:18
















    • What happens if $q=r$?
      – Michael Rozenberg
      Aug 3 at 19:04






    • 1




      If $q=r$ we get no quadratic equation.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:07










    • Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
      – Dr. Sonnhard Graubner
      Aug 3 at 19:11










    • I think it's enough $x=1$.
      – Michael Rozenberg
      Aug 3 at 19:12










    • Ok, so i will sleep better Michael.
      – Dr. Sonnhard Graubner
      Aug 3 at 19:18















    What happens if $q=r$?
    – Michael Rozenberg
    Aug 3 at 19:04




    What happens if $q=r$?
    – Michael Rozenberg
    Aug 3 at 19:04




    1




    1




    If $q=r$ we get no quadratic equation.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:07




    If $q=r$ we get no quadratic equation.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:07












    Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
    – Dr. Sonnhard Graubner
    Aug 3 at 19:11




    Then if $$rne p$$ we get $$x=1$$ and $$x=0$$ or $$x=1$$
    – Dr. Sonnhard Graubner
    Aug 3 at 19:11












    I think it's enough $x=1$.
    – Michael Rozenberg
    Aug 3 at 19:12




    I think it's enough $x=1$.
    – Michael Rozenberg
    Aug 3 at 19:12












    Ok, so i will sleep better Michael.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:18




    Ok, so i will sleep better Michael.
    – Dr. Sonnhard Graubner
    Aug 3 at 19:18










    up vote
    0
    down vote













    Consider the polinomial of degree 2 vector space. Let $a in mathbbR$ such as $(q - r, r - p, p - q) = a(r - p, p - q, q - r) iff begincases
    q - r - ar + ap = 0\
    r - p -ap + aq = 0\
    p - q -aq + ar = 0
    endcases
    $. Then
    $left(beginarrayccc
    a & 1 & -1-a\
    -1-a & a & 1\
    1 & -1-a & a
    endarrayright)left(beginarrayccc
    p\
    q\
    r
    endarrayright) = left(beginarrayccc
    0\
    0\
    0
    endarrayright)$ and $left|beginarrayccc
    a & 1 & -1-a\
    -1-a & a & 1\
    1 & -1-a & a
    endarrayright| = 0$
    Hence,the set $S = (q - r)x^2 + (r - p)x + p - q, (r - p)x^2 + (p - q)x + (q - r)$ is linear dependent. The dimension of space generated by $S$ is least equal 1 and the kernel dimension is great or equal 2. Hence, the equation system are at least one common solution.






    share|cite|improve this answer



























      up vote
      0
      down vote













      Consider the polinomial of degree 2 vector space. Let $a in mathbbR$ such as $(q - r, r - p, p - q) = a(r - p, p - q, q - r) iff begincases
      q - r - ar + ap = 0\
      r - p -ap + aq = 0\
      p - q -aq + ar = 0
      endcases
      $. Then
      $left(beginarrayccc
      a & 1 & -1-a\
      -1-a & a & 1\
      1 & -1-a & a
      endarrayright)left(beginarrayccc
      p\
      q\
      r
      endarrayright) = left(beginarrayccc
      0\
      0\
      0
      endarrayright)$ and $left|beginarrayccc
      a & 1 & -1-a\
      -1-a & a & 1\
      1 & -1-a & a
      endarrayright| = 0$
      Hence,the set $S = (q - r)x^2 + (r - p)x + p - q, (r - p)x^2 + (p - q)x + (q - r)$ is linear dependent. The dimension of space generated by $S$ is least equal 1 and the kernel dimension is great or equal 2. Hence, the equation system are at least one common solution.






      share|cite|improve this answer

























        up vote
        0
        down vote










        up vote
        0
        down vote









        Consider the polinomial of degree 2 vector space. Let $a in mathbbR$ such as $(q - r, r - p, p - q) = a(r - p, p - q, q - r) iff begincases
        q - r - ar + ap = 0\
        r - p -ap + aq = 0\
        p - q -aq + ar = 0
        endcases
        $. Then
        $left(beginarrayccc
        a & 1 & -1-a\
        -1-a & a & 1\
        1 & -1-a & a
        endarrayright)left(beginarrayccc
        p\
        q\
        r
        endarrayright) = left(beginarrayccc
        0\
        0\
        0
        endarrayright)$ and $left|beginarrayccc
        a & 1 & -1-a\
        -1-a & a & 1\
        1 & -1-a & a
        endarrayright| = 0$
        Hence,the set $S = (q - r)x^2 + (r - p)x + p - q, (r - p)x^2 + (p - q)x + (q - r)$ is linear dependent. The dimension of space generated by $S$ is least equal 1 and the kernel dimension is great or equal 2. Hence, the equation system are at least one common solution.






        share|cite|improve this answer















        Consider the polinomial of degree 2 vector space. Let $a in mathbbR$ such as $(q - r, r - p, p - q) = a(r - p, p - q, q - r) iff begincases
        q - r - ar + ap = 0\
        r - p -ap + aq = 0\
        p - q -aq + ar = 0
        endcases
        $. Then
        $left(beginarrayccc
        a & 1 & -1-a\
        -1-a & a & 1\
        1 & -1-a & a
        endarrayright)left(beginarrayccc
        p\
        q\
        r
        endarrayright) = left(beginarrayccc
        0\
        0\
        0
        endarrayright)$ and $left|beginarrayccc
        a & 1 & -1-a\
        -1-a & a & 1\
        1 & -1-a & a
        endarrayright| = 0$
        Hence,the set $S = (q - r)x^2 + (r - p)x + p - q, (r - p)x^2 + (p - q)x + (q - r)$ is linear dependent. The dimension of space generated by $S$ is least equal 1 and the kernel dimension is great or equal 2. Hence, the equation system are at least one common solution.







        share|cite|improve this answer















        share|cite|improve this answer



        share|cite|improve this answer








        edited Aug 3 at 19:30


























        answered Aug 3 at 19:16









        GinoCHJ

        12




        12












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