Question

已知2^a=3,2^b=6,2^c=12,則a,b,c

1. A.
   成等差數(shù)列但不成等比數(shù)列
2. B.
   成等比數(shù)列但不成等差數(shù)列
3. C.
   既成等差數(shù)列又成等比數(shù)列
4. D.
   既不成等比數(shù)列又不成等差數(shù)列

Answer 1

A
∵a=log₂3,b=log₂6,c=log₂12,又∵log₂3+log₂12=log₂36=2log₂6,∴2b=a+c.故a,b,c成等差數(shù)列但不成等比數(shù)列.