Problems

Find the minimum for all $\alpha$, $\beta$ of the maximum of the function $y(x)=|\cos x+\alpha \cos 2x+\beta \cos 3x|$.

Is there a line on the coordinate plane relative to which the graph of the function $y=2^x$ is symmetric?

In a dark room on a shelf there are 4 pairs of socks of two different sizes and two different colours that are not arranged in pairs. What is the minimum number of socks necessary to move from the drawer to the suitcase, without leaving the room, so that there are two pairs of socks of different sizes and colours in the suitcase?

The function $f(x)$ for each real value of $x\in (-\mathrm{\infty },+\mathrm{\infty })$ satisfies the equality $f(x)+(x+1/2)\times f(1-x)=1$.

a) Find $f(0)$ and $f(1)$. b) Find all such functions $f(x)$.

Aladdin visited all of the points on the equator, moving to the east, then to the west, and sometimes instantly moving to the diametrically opposite point on Earth. Prove that there was a period of time during which the difference in distances traversed by Aladdin to the east and to the west was not less than half the length of the equator.

In the numbers of MEXAILO and LOMONOSOV, each letter denotes a number (different letters correspond to different numbers). It is known that the products of the numbers of these two words are equal. Can both numbers be odd?

The numbers $a$ and $b$ are such that the first equation of the system $$\begin{array}{rl}\sin x+a& =bx\\ \cos x& =b\end{array}$$ has exactly two solutions. Prove that the system has at least one solution.

The numbers $a$ and $b$ are such that the first equation of the system $$\begin{array}{rl}\cos x& =ax+b\\ \sin x+a& =0\end{array}$$ has exactly two solutions. Prove that the system has at least one solution.

Determine all natural numbers $m$ and $n$ such as $m!+12=n^2$.

A game with 25 coins. In a row there are 25 coins. For a turn it is allowed to take one or two neighbouring coins. The player who has nothing to take loses.