title: 若2^t=1/e^π,t∈[k,k+1),k∈Z,则k的值为() 
desc: 若2^t=1/e^π，t∈[k,k+1),　k∈Z,　则k的值为(      )
  A.-5 
  B.-4 
  .-3 
  D.-2 
answer: 若2^t=1/e^π，t∈[k,k+1),　k∈Z,　则k的值为( ) 
  
  2^t=1/e^π--->2^(-t)=e^π≈(2.7)³≈20∈(16,32)
  --->-t∈(4,5]--->t∈[-5,-4)--->k=-5...............A