Вариант 30 ИДЗ 5.2

EDS - 5.2
№1.30 Prove that the functions f (x) = cos 3x - cos5x; φ (x) = x2 as x → 0 are infinitesimal of the same order of smallness.
№2.30 Find the limits.
№3.30 Investigate these functions for continuity and build their graphs.
№4.30 Investigate these functions for continuity at the specified points. f (x) = (x + 1) / (x-2); x1 = 2; x2 = 3;