Ryabushko A.P. IDZ 5.2 option 9

DHS - 5.2
№1.9 Prove that the function f (x) = 3x / (1-x); φ (x) = x / (x + 4) as x → 0 are the infinitesimal of the same order of smallness.
№2.9 Find limits.
№3.9 investigate these functions continuity and build their schedules.
№4.9 investigate these functions continuity at these points. f (x) = ....; x1 = 3; x2 = 4;