If x 2 + p x − 4 4 4 p = 0 has integral roots where p is a prime number , then find the value of p
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
We can rewrite the equation in two other forms, as : x 2 + p x + ( − 1 4 8 ) × 3 p = 0 or x 2 + p x + 1 4 8 × ( − 3 p ) = 0 . It is clear that − 1 4 8 + 3 p = p and 1 4 8 + ( − 3 p ) = p , then we get p = − 7 4 and p = 3 7 respectively. Since p is prime, hence p = 3 7 .
Simple middle term splitting method can help to solve it x^2 +px-444p=0 444=37×4×3×p 37×4-3p=p p=37
I have no proper solution...Discriminant id p^2+1776p...Use a calculator and keep substituting primes to make it a perfect square....personally...i dont think the question to be "cool"...is there a better way??
I did the same thing.
i also did the same thing there was nothing cool in this problem
even 222 can be the answer
Log in to reply
Its mentioned that p is a prime number...222 is not...
Problem Loading...
Note Loading...
Set Loading...
I have a proper solution. The roots are integers. We know that x+y=-p and xy=444p. So xy is a multiple of p. But p divides xy if p divides either x or y. Let's say that p divides x. Which means that x=np, but we know that x+y=-p which gives that y=-p-np=-(n+1)p. Now we'll use the product: xy=444p. Which means that -n(n+1)p^2=444p. Which means that p^2 divides 444p, which gives p divides 444. Since p is prime and a divisor of 444 then p can only be 2, 3 or 37. Then plug those values of p in the equation and check if the roots are integers. The discriminant is a square number only when p=37. The other solutions are incomplete or simple guesses.