lim(x趋于o) (3^x-1)sinx^3 / ln(1+x^4)
=
lim(x趋于o) (3^x-1)*x^3 / (x^4)
=lim(x趋于o) (3^x-1) / x
=lim(x趋于o) 3^x*ln3) / 1
=ln3