Find the relation between p, q and r if one root of the equation px^2+qx+r=0 is double of the other

x^2 + q/p x + r/p = 0

(x - s ) (x - 2s) = 0 ----> x^2 - 3 s x + 2 s^2 = 0

-3 s x = (q/p) x
2 s^2 = r/p

s =-q p/3
2 (q^2 p^2/9) = r/p