Question 5
Let $d$ be a positive divisor of $5+1998^{1998}$. Prove that $d$ can be written as $d=2x^2+2xy+3y^2$ with integers $x,y$ if and only if its remainder upon division by 20 is 3 or 7.
The supplied source has no question point values. Each problem uses 1 editorial point for import compatibility; this is not an official scoring scale.
The supplied source has no question point values. Each problem uses 1 editorial point for import compatibility; this is not an official scoring scale.