解
2^m=a
2^n=b——这个吧
2^(m+n)
=2^m×2^n
=ab
4^(m+n)
=4^m×4^n
=(2²)^m×(2²)^n
=(2^m)²×(2^n)²
=a²b²
2^2n+2^3n
=(2^n)²+(2^n)³
=b²+b³