(1).(x+2y-3z)(x-2y+3z) = [x+(2y-3z)] [x-(2y-3z)] =x²-(2y-3z)²=x²-(4y²-12yz+9z²)=x²-4y²+12yz-9z²(2).(x+2y-1)²=[(x+2y)－1]²=(x+2y)²-2(x+2y)+1=x...