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Finding Real roots of a polynomial


Finding the real roots of a polynomialPolynomial roots questionShow that the equation $x^4 + rx + s = 0$ has at most two distinct real roots.Polynomial with real rootsThe sum of non real roots of the polynomial equation $x^3+3x^2+3x+3=0$When does $nx^4+4x+3=0$ have real roots?Polynomial with odd number of real rootsCondition on $a$ for $(x^2+x)^2+a(x^2+x)+4=0$Postive and negative real rootsFind the number of distinct real roots of a polynomial













0












$begingroup$


Find all real values of $a$ for which the equation
$(x^2 + a)^2 + a = x$ has four real roots.



Can someone help me with this? I have no idea how to start this.










share|cite|improve this question









$endgroup$











  • $begingroup$
    It seems as if $a<-0.7$... See here.
    $endgroup$
    – clathratus
    Mar 29 at 2:53










  • $begingroup$
    Is this pre-calculus?
    $endgroup$
    – Andrei
    Mar 29 at 3:15






  • 1




    $begingroup$
    if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
    $endgroup$
    – Vasya
    Mar 29 at 3:35















0












$begingroup$


Find all real values of $a$ for which the equation
$(x^2 + a)^2 + a = x$ has four real roots.



Can someone help me with this? I have no idea how to start this.










share|cite|improve this question









$endgroup$











  • $begingroup$
    It seems as if $a<-0.7$... See here.
    $endgroup$
    – clathratus
    Mar 29 at 2:53










  • $begingroup$
    Is this pre-calculus?
    $endgroup$
    – Andrei
    Mar 29 at 3:15






  • 1




    $begingroup$
    if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
    $endgroup$
    – Vasya
    Mar 29 at 3:35













0












0








0


1



$begingroup$


Find all real values of $a$ for which the equation
$(x^2 + a)^2 + a = x$ has four real roots.



Can someone help me with this? I have no idea how to start this.










share|cite|improve this question









$endgroup$




Find all real values of $a$ for which the equation
$(x^2 + a)^2 + a = x$ has four real roots.



Can someone help me with this? I have no idea how to start this.







algebra-precalculus






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Mar 29 at 2:48









sumisumi

634




634











  • $begingroup$
    It seems as if $a<-0.7$... See here.
    $endgroup$
    – clathratus
    Mar 29 at 2:53










  • $begingroup$
    Is this pre-calculus?
    $endgroup$
    – Andrei
    Mar 29 at 3:15






  • 1




    $begingroup$
    if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
    $endgroup$
    – Vasya
    Mar 29 at 3:35
















  • $begingroup$
    It seems as if $a<-0.7$... See here.
    $endgroup$
    – clathratus
    Mar 29 at 2:53










  • $begingroup$
    Is this pre-calculus?
    $endgroup$
    – Andrei
    Mar 29 at 3:15






  • 1




    $begingroup$
    if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
    $endgroup$
    – Vasya
    Mar 29 at 3:35















$begingroup$
It seems as if $a<-0.7$... See here.
$endgroup$
– clathratus
Mar 29 at 2:53




$begingroup$
It seems as if $a<-0.7$... See here.
$endgroup$
– clathratus
Mar 29 at 2:53












$begingroup$
Is this pre-calculus?
$endgroup$
– Andrei
Mar 29 at 3:15




$begingroup$
Is this pre-calculus?
$endgroup$
– Andrei
Mar 29 at 3:15




1




1




$begingroup$
if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
$endgroup$
– Vasya
Mar 29 at 3:35




$begingroup$
if it has $4$ real roots, you should be able to write it as a product of two quadratic polynomials with real roots (i.e. positive discriminant)
$endgroup$
– Vasya
Mar 29 at 3:35










1 Answer
1






active

oldest

votes


















3












$begingroup$

Hint: $(x^2+a)^2 + a - x = (x^2 + x + a + 1)(x^2 - x + a)$. When do these quadratic factors have two real roots each?






share|cite|improve this answer









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    1 Answer
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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    Hint: $(x^2+a)^2 + a - x = (x^2 + x + a + 1)(x^2 - x + a)$. When do these quadratic factors have two real roots each?






    share|cite|improve this answer









    $endgroup$

















      3












      $begingroup$

      Hint: $(x^2+a)^2 + a - x = (x^2 + x + a + 1)(x^2 - x + a)$. When do these quadratic factors have two real roots each?






      share|cite|improve this answer









      $endgroup$















        3












        3








        3





        $begingroup$

        Hint: $(x^2+a)^2 + a - x = (x^2 + x + a + 1)(x^2 - x + a)$. When do these quadratic factors have two real roots each?






        share|cite|improve this answer









        $endgroup$



        Hint: $(x^2+a)^2 + a - x = (x^2 + x + a + 1)(x^2 - x + a)$. When do these quadratic factors have two real roots each?







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Mar 29 at 3:49









        Robert IsraelRobert Israel

        330k23219473




        330k23219473



























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