问题
填空题
已知三数x+log272，x+log92，x+log32成等比数列，则公比为______．
答案
∵三数x+log272，x+log92，x+log32成等比数列
∴q=
=x+log92 x+log272
=x+log32 x+log92 log92-log32 log272-log92
而log92=
log32，log272=1 2
log321 3
∴q=
=log92-log32 log272-log92
=3
log 32-log 321 2
log32-1 3
log321 2
故答案为：3