Let $x^2-ax+b=0$ be a second degree equation, where $x, a$ and $b$ are all positive integers greater than 0. Then, for a given $a$,

  1. Can we calculate how many different values of $b$ are there?
  2. Can we calculate the divisors of $b$? And its primality?
  3. Is there any other "important" characteristic about $b$ that we could obtain?
  4. (Would it be possible to know the exact values of $b$?)
  • $\begingroup$ If all of $x,a$ and $b$ are positive then this equation has no solutions. Maybe $x$ is not positive. $\endgroup$
    – Anurag A
    Dec 13, 2016 at 19:53

1 Answer 1


if x, a and b are all integers. Then the roots of the polynomial are integers.

$(x+r_1)(x+r_2) = x^2 + ax + b = 0$

In order for $a$ and $b$ to both be greater than $0,$ then $r_1, r_2$ must be greater than 0.

But that would indicate that $x<0$

There is no polynomial that meets the required conditions.

  • $\begingroup$ Thank you very much and sorry for my mistake... $\endgroup$ Dec 13, 2016 at 20:15

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .