2^m*2^m*4=2^82^m*2^m*2^2=2^82^(2m+2)=2^82m+2=8m=3
2^m×2^m×4=2^82^(2m+2)=2^82m+2=8m=3
2^m × 2^m × 4=2^82^(m+m+2)=2^82m+2=8m=3