Вариант 5 ИДЗ 5.2

EDS - 5.2
№1.5 Prove that the functions f (x) = cos 3x - cos x; φ (x) = 7x2 as x → 0 are infinitesimal of the same order of smallness.
№2.5 Find the limits.
№3.5 Investigate these functions for continuity and build their graphs.
№4.5 Investigate these functions for continuity at the specified points. f (x) = ....; x1 = 2; x2 = 3;