【简答题】设x∈N + 时f(x)∈N + ,对任何n∈N+有f(n+1)>f(n)且f(f(n))=3n, (1)求f(1); (2)求f(6)+f(7); (3)求f(2012).
【简答题】在直流电路中电感元件相当于() A短路 B开路 C通路 D不一定
【单选题】—How do you look after your goldfish? —They need clean water, and remember not to _____ with your hands.
【简答题】已知f(n)=cos nπ 4 (n∈N * ),则f(1)+f(2)+f(3)+…+f(100)=______.