int (e +00) dx/(x * ln^4 x) = int (e +00) 1/ln^4 x d(ln x) = | ln x = t | =
= int (1 +00) 1/t^4 dt = int (1 +00) t^(-4) dt = lim (a->+00) int (1 a) t^(-4) dt =
= lim (a->+00) (1/(-4 + 1) * t^(-4 + 1))_{1}^{a} =
= lim (a->+00) (-1/3 * t^(-3))_{1}^{a} = lim (a->+00) (-1/3 * 1/t^3)_{1}^{a} =
= lim (a->+00) (-1/3 * 1/a^3 + 1/3 * 1/1^3) = lim (a->+00) (1/3 - 1/3 * 1/a^3) =
= 1/3 - 1/3 * 0 = 1/3.