原式=3的2m次-3的4n次+3
=6的2次-2的4次+3
=36-16+3
=23 3^(2m-4n+1)=6^2*2^(-4)*3=36*3/16=27/4 3的2m-4n+1
=3的2m次 除以 3的4n次方 乘以 3的
=6*6 ÷ （2*2*2*2）×3
=36÷16×3
=27/4 由题意： 3^m=63^n=2
3^(2m-4n+1)
=3^(2m)*3^(-4n)*3
=(3^m)^2*[3^(n)]^(-4)*3
=6^2*2^(-4)*3
=108*1/16
=27/4