We can simplify the expressions using the ratio test.

  • lim 3^n/n^3: divide by (3/2)^n
    • lim (3/2)^n / n^3
    • Using L'Hopital's rule, we get lim (ln(3/2)/3) / n^3 which is 0 as n goes to infinity.
    • Therefore, lim 3^n/n^3 is 0.
  • lim 3^n/n!: divide by (3/2)^n
    • lim (3/2)^n / n!
    • Using Stirling's approximation, we get lim (3/2)^n / sqrt(2πn) (n/e)^n which is infinity as n goes to infinity.
    • Therefore, lim 3^n/n! is infinity.

In summary:

  • lim 3^n/n^3 = 0
  • lim 3^n/n! = infinit

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