1. My Russian is a bit rusty. I think you're asking to find the antiderivatives in the first part:

а) [tex]\displaystyle \int 2x^n - 5x \, dx = \boxed{\frac2{n+1} x^{n+1} - \frac52 x^2 + C}[/tex]

This follows from the power rule for differentiation,

[tex]\dfrac d{dx} x^n = n x^{n-1}[/tex]

I'm not sure what the power on the first term is, so I just use a general real number n. This solution is correct as long as n ≠ -1; otherwise we would have

[tex]\displaystyle \int 2x^{-1} - 5x = 2\ln|x| - \frac52 x^2 + C[/tex]

б) Using the fact that

[tex]\dfrac d{dx} \sin(x) = \cos(x)[/tex]

as well as the power rule from part (a),

[tex]\displaystyle \int 3 \cos(x) - x \, dx = \boxed{3 \sin(x) - \frac12 x^2 + C}[/tex]

в) By the chain rule,

[tex]\dfrac d{dx} \sin(5x) = 5 \cos(5x)[/tex]

[tex]\dfrac d{dx} \cos(3x) = -3 \sin(3x)[/tex]

Hence

[tex]\displaystyle \int \cos(5x) - \frac16 \sin(3x) \, dx = \boxed{\frac15 \sin(5x) + \frac1{18} \cos(3x) + C}[/tex]

2. These just look like standard definite integrals. Using the known derivatives mentioned in part (1) in conjunction with the fundamental theorem of calculus, we have

a)

[tex]\displaystyle \int_0^1 x^2 \, dx = \frac13 x^3 \bigg|_{x=0}^{x=1} = \frac13 (1^3 - 0^3) = \boxed{\frac13}[/tex]

б)

[tex]\displaystyle \int_0^{\frac\pi2} \sin(x) \, dx = -\cos(x) \bigg|_{x=0}^{x=\frac\pi2} = -\left(\cos\left(\frac\pi2\right) - \cos(0)\right) = \boxed{1}[/tex]