Results 1 to 6 of 6

Math Help - X^2 + kX + P = 0 where p is prime and k is an integer has two +ve solns. k + p = ?

  1. #1
    Junior Member
    Joined
    Aug 2010
    Posts
    25

    X^2 + kX + P = 0 where p is prime and k is an integer has two +ve solns. k + p = ?

    Let p be a prime number and K an integer such that X^2 + kX + P = 0 has two positive interger solutions . What is the value of K+P?
    Last edited by mr fantastic; September 7th 2010 at 03:56 AM. Reason: Re-titled.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    A Plied Mathematician
    Joined
    Jun 2010
    From
    CT, USA
    Posts
    6,318
    Thanks
    5
    Awards
    2
    What ideas have you had so far?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Aug 2010
    Posts
    25
    I try to solve this question by using delta= b^2-4ac but it does not work
    Follow Math Help Forum on Facebook and Google+

  4. #4
    A Plied Mathematician
    Joined
    Jun 2010
    From
    CT, USA
    Posts
    6,318
    Thanks
    5
    Awards
    2
    Well, the discriminant, which is your delta, is going to be important. However, it's not everything. What kind of equation to you have there? And how do you normally solve it?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member
    Joined
    Jun 2009
    Posts
    806
    Thanks
    4
    If α and β are the roots of a quadratic equation ax^2 + bx + c = 0, then the sum of the roots = -b/a and the product of the roots = c/a.

    In the given problem α + β = - k and αβ = p.

    Since p is a prime, α = p and β = 1.

    So α + β = - k = p + 1.

    Hence k + p = -1.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Junior Member
    Joined
    Aug 2010
    Posts
    25
    thanks
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Congruence, prime number, integer
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: June 8th 2011, 09:10 AM
  2. Proving that the additive integer is prime...
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: September 25th 2009, 02:06 PM
  3. Replies: 2
    Last Post: June 9th 2009, 03:05 AM
  4. Positive Integer is Prime Like
    Posted in the Number Theory Forum
    Replies: 14
    Last Post: May 4th 2009, 08:57 AM
  5. Proving an integer is prime
    Posted in the Number Theory Forum
    Replies: 2
    Last Post: September 12th 2005, 04:25 PM

Search Tags


/mathhelpforum @mathhelpforum