Question 57
Two different integers $u$ and $v$ are written on a board. We perform a sequence of steps. At each step we do one of the following two operations:
(i) If $a$ and $b$ are different integers on the board, then we can write $a+b$ on the board, if it is not already there.
(ii) If $a, b$ and $c$ are three different integers on the board, and if an integer $x$ satisfies $a x^{2}+b x+c=0$, then we can write $x$ on the board, if it is not already there.
Determine all pairs of starting numbers $(u, v)$ from which any integer can eventually be written on the board after a finite sequence of steps.
(i) If $a$ and $b$ are different integers on the board, then we can write $a+b$ on the board, if it is not already there.
(ii) If $a, b$ and $c$ are three different integers on the board, and if an integer $x$ satisfies $a x^{2}+b x+c=0$, then we can write $x$ on the board, if it is not already there.
Determine all pairs of starting numbers $(u, v)$ from which any integer can eventually be written on the board after a finite sequence of steps.