Помогите найти первообразную функции

1) F (X) = 2x-5x

2) F (X) = 3cosx-x

3) F (X) = cos5x-1/6sin3x

F (x) = 2x-5x

∫ 2x-5x dx = x² - (5/2) x²+C

f (x) = x² - (5/2) x²+C

F (x) = 3cos (x) - x

∫ 3cos (x) - x dx = 3∫ cos (x) dx - ∫ x dx = 3sin (x) - (1/2) x²+C

f (x) = 3sin (x) - (1/2) x²+C

F (x) = cos5x-1/6sin3x

∫ cos5x - 1/6sin3x dx = 1/5 sin5x+1/18cos3x+C

f (x) = 1/5sin5x+1/18cos3x+C