1.（a+b)²+2(a+b)+1 =[(a+b)+1]²=(a+b+1)²2.m²(m-1)-4(1-m)² =m²(m-1)-4(m-1)²=(m-1)(m²-4m+4)=(m-1)(m-2)²3.x²-y²-2y-1 =x²-(y²+2y+1)=x²-...