[x--> -3] Lim(sin(x+3)/(x³ +3³) =[x--> -3] Lim(sin(x+3)/((x+3)(x² -3x +9)) =
=[x--> -3] Lim(sin(x+3)/(x+3) *1/x² -3x +9)) = 1*1/((-3)² -3 *(-3) +9) =1/27 .
----------------------------------------------------------------------
[x--> -3] Limsin(x+3)/(x+3) =
[t--> 0 ] Lim sint/t = 1 ( при x --> -3 ⇒ t=x+3 -->0).