3+4^m
=3+2^2m
=3+2^(2m+2)÷4
=3+[2^(m+1)]^2÷4
y=3+x²/4能说的详细点吗 我还是不懂啊哪一步不懂?3+2^(2m+2)÷4这一步怎么来的啊2^2m=2^(2m+2-2)=2^(2m+2)÷2^2=3+2^(2m+2)÷4