Polynomials do or don't have integer roots?

In summary, the polynomial almost certainly has rational coefficients. If it doesn't have any rational coefficients, then the only solution is s or its factors. The only way to determine whether any of those solutions are valid is to try them in the equation.
  • #1
povatix
8
0

Homework Statement



Is it there a method to find out if a polynomial has no integer roots?


The Attempt at a Solution


I tried the division of polynomials, as well as the Horner's Method, but no luck.
 
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  • #2
povatix said:

Homework Statement



Is it there a method to find out if a polynomial has no integer roots?


The Attempt at a Solution


I tried the division of polynomials, as well as the Horner's Method, but no luck.

Use "rational root theorem".
 
  • #3
Doesn't the rational root theorem only apply to polynomials over the rationals?
 
  • #4
Yes, basically. Is there a method for general real polynomials?
 
  • #5
Povatix,

Does the polynomial itself have integer coefficients? If so, you can use Eisenstein's criterion.
 
  • #6
abelian jeff said:
Povatix,

Does the polynomial itself have integer coefficients? If so, you can use Eisenstein's criterion.

Irreducible is sufficient to show there is no rational root, but it's not necessary. Kummer was right. Just check all the possible rational roots, if none are integers, then there are none. The OP's polynomial almost certainly has rational coefficients. And if it doesn't I wish they had displayed it.
 
  • #7
Here's the equation.

[tex]\chi^{10} + p\chi^{9} - q\chi^{7} + r\chi^{4} - s = 0[/tex]

thnx in advance
 
  • #8
If the coefficients are all integers, then the only possible integer solutions are s or its factors. The only way I know of determining whether any of those ARE solutions is to try them in the equation. Are you doing this for specific values of p, q, r, s? Obviously, the equation you give will have integer values for some values of p, q, r, s and not for others.
 
  • #9
Oh right, sorry, the question also states that p q r and s are all odd integers
 
  • #10
If x is an odd integer, then so is any power of it and so is any odd integer times any power. What can you say about the sum (or difference) of 5 odd integers?

If x is an even integer, then so is any power of it and so is any integer times any power. What can you say about the sum (or difference) of 4 even integers. In order that the value of the polynomial be 0, what must s be?

It would have helped a lot if you had given us all this information to begin with!
 
  • #12
Yes, it's true. This is part of a much larger enrichment program aimed at the top students in Year 10, which includes a textbook that is meant to aid you through the 16 questions.

P.S. How did you find out?
 
  • #13
I'm Psychic =]

Jokes, I did it this year too. You will like that thread then, it has a lot of other questions from the program :)
 

What are polynomials?

Polynomials are mathematical expressions that consist of variables, coefficients, and exponents. They can be written in the form of ax^n + bx^(n-1) + ... + c, where a, b, and c are constants and n is a non-negative integer.

Do polynomials always have integer roots?

No, polynomials do not always have integer roots. Some polynomials, such as x^2 + 1, do not have any real roots, let alone integer roots.

How can you determine if a polynomial has integer roots?

A polynomial with integer roots will have factors that are also integers. Therefore, you can use the Rational Root Theorem to determine potential integer roots by finding all possible factors of the constant term and dividing them by all possible factors of the leading coefficient. If any of these potential roots evaluate to 0 when substituted into the polynomial, then they are integer roots.

What if a polynomial has complex roots?

If a polynomial has complex roots, it means that the roots are not real numbers but rather involve the imaginary unit i. Complex roots come in conjugate pairs, so if a + bi is a root, then a - bi is also a root. In this case, the polynomial does not have any integer roots.

What happens if a polynomial has repeated roots?

If a polynomial has repeated roots, it means that one or more of the roots have a multiplicity greater than 1. This means that the polynomial touches or crosses the x-axis at that root, rather than crossing through it. In this case, the polynomial may have integer roots, but not necessarily distinct integer roots.

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