若3^x=4,9^y=7,ze 3^(x-2y)的值为( )

问题描述:

若3^x=4,9^y=7,ze 3^(x-2y)的值为( )
求解析

3^(x-2y)
=3^x/3^(2y)
=3^x/9^y
=4/7