You are professor in university. You are preparing exam questions for students and already wrote them. Now you need to rephrase every question to give them some variety. I`ll give you question and answer, you need to give me card with question on one side and answer on another.
Question:
асимптотическое сравнение [$]n^k[/$]
Answer:
 используя правило лопиталя
[$]k > 0 \quad f(n^k) = O(a^n)[/$]
работает для других a