=(2m)²+2×2m×1+1²
=(2m+1)²又补充了一个，帮忙解一下，谢谢9a^2-24ab+16b^2=(3a)²-2× 3a×4b+(4b)²=(3a-4b)² -m^2-m-1/4=-(m²+m+1/4)=-(m+1/2)²