中三數學--指數定律

1. =2^n(9)/2^n(4)
=9/4

未必岩→2. =9(2^2n)-3(2^n+1) / 5(2^n-1)
=2^n-1(9*2^n+1) - 3(4))/5(2^n-1)
=9(2^n+1) - 12 / 5
=3((2n+1)-4) / 5

2^(2n+1)=2^2n * 2
2^2n 唔=2^n
想問上面果個人點解可以將2^2n 同2^n 一齊約?