Here are the functions from the image:

Variant 9, 19:

1. $f(x) = \frac{2}{x^4} + 3x^3 - 5x + 1$ on $(0; +\infty)$
2. $f(x) = 2\sin(4x) + 3$ on $(-\infty; +\infty)$
3. $f(x) = 2 - 6x^2$ on $(-\infty; +\infty)$
4. $f(x) = \frac{3}{\cos^2(3x)}$, with $M(\frac{\pi}{3}; 1)$

Variant 5, 15:

1. $f(x) = 2 - 2x^3 + \frac{3}{x^4} + x$ on $(0; +\infty)$
2. $f(x) = 5\sin(x) + 2$ on $(-\infty; +\infty)$
3. $f(x) = (5 - 9x)^8$ on $(-\infty; +\infty)$
4. $f(x) = 2 \cos\left(x - \frac{\pi}{3}\right)$, with $M(\frac{\pi}{3}; 2)$

Would you like to go through the solutions or any specific function in detail?