4^N/5^N小于2/55^N大于0,同时乘以它,再除以2,得到2^(2N-1)小于5^(N-1)取对数(2N-1)LOG2小于(N-1)LOG5(LOG5-2LOG2)N大于LOG5-LOG2N大于(LOG5-LOG2)/(LOG5-2LOG2)N大于(LOG5-LOG2)/(LOG5-LOG4)n为正整数得,N大于4...