Question

计算(x+y-3)(x-y+3)

计算(x+y-3)(x-y+3)
要快，我今天就要答案，急啊
还有（x－2y＋3z）^2

Answer 1

=[x+（y-3）][x-（y-3）]
=x²-（y-3）²
=x²-y²+6y-9

Answer 2

(x+y-3)(x-y+3)
=x的平方-（3-y) 的平方
=x^2-y^2+6y-9

Answer 3

（x+y-3）(x-y+3)=[x+(y-3)][x-(y-3)]=x^2-(y-3)^2=x^2-(y^2-6y+9)

Answer 4

x^2-(y-3)^2=x^2-y^2+6y-9

追问

还有（x－2y＋3z）^2,要快啊

追答

(x-2y)^2+(3z)^2+6z(x-2y)
=x^2+4y^2-4xy+9z^2+6xz-12zy

Answer 5

-(x+y-3)的平方