Question 141
Rational numbers $a$ and $b$ satisfy the equality
$$
a^3 b + ab^3 + 2a^2 b^2 + 2a + 2b + 1 = 0.
$$
Prove that $1 - ab$ is a square of a rational number. (R. Zhenodarov)
$$
a^3 b + ab^3 + 2a^2 b^2 + 2a + 2b + 1 = 0.
$$
Prove that $1 - ab$ is a square of a rational number. (R. Zhenodarov)