Question 2
Let $x,y$ be integers with $x\ne-1$, $y\ne-1$, such that
$$\frac{x^4-1}{y+1}+\frac{y^4-1}{x+1}$$
is an integer. Prove that $x^4y^{44}-1$ is divisible by $x+1$.
$$\frac{x^4-1}{y+1}+\frac{y^4-1}{x+1}$$
is an integer. Prove that $x^4y^{44}-1$ is divisible by $x+1$.