（a+b）²-1=（a+b+1)(a+b-1)-（x+2）²+16（x-1）²=[4(x-1)+(x+2)][4（x-1)-(x+2)]=(4x-4+x+2)(4x-4-x-2)=(5x-2)(3x-6)=3(x-2)(5x-2)（3x+2y）²-（x-y）²=[(3x+2y)+(x-y)][(3x+2y)-(x-y)]=(...