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
答
3^(x-2y)
=3^x/3^(2y)
=3^x/9^y
=4/7