In this paper, we have presented a selection of problems from the Russian Math Olympiad, along with their solutions. These problems demonstrate the challenging and elegant nature of the competition, and we hope that they will inspire readers to explore mathematics further.
(From the 2007 Russian Math Olympiad, Grade 8)
We have $f(f(x)) = f(x^2 + 4x + 2) = (x^2 + 4x + 2)^2 + 4(x^2 + 4x + 2) + 2$. Setting this equal to 2, we get $(x^2 + 4x + 2)^2 + 4(x^2 + 4x + 2) = 0$. Factoring, we have $(x^2 + 4x + 2)(x^2 + 4x + 6) = 0$. The quadratic $x^2 + 4x + 6 = 0$ has no real roots, so we must have $x^2 + 4x + 2 = 0$. Applying the quadratic formula, we get $x = -2 \pm \sqrt{2}$.
(From the 2001 Russian Math Olympiad, Grade 11)