Вариант 18 ИДЗ 5.2

EDS - 5.2
№1.18. Prove that the functions f (x) = tg (x2 + 2x); φ (x) = x2 + 2x as x → 0 are infinitesimal of the same order of smallness.
№2.18 Find the limits.
№ 3.18 Investigate these functions for continuity and build their graphs.
# 4.18. Investigate these functions for continuity at the specified points. f (x) = 3x / (x - 4); x1 = 4; x2 = 5.