已知9^m=3,9^n=4,则9^2m-n等于( )如题,请写出步骤.

问题描述:

已知9^m=3,9^n=4,则9^2m-n等于( )
如题,请写出步骤.

9^2m-n
=9^2m÷9^n
=(9^m)^2÷9^n
=3^2÷4
=9/4