下列各式相乘时,可以利用平方差公式的是 A.(-x-y)(x-y) B.(-x-y)(x+y) C.(x-y)(-x+y) D.(x-y-z)(-x+y+z)

问题描述:

下列各式相乘时,可以利用平方差公式的是 A.(-x-y)(x-y) B.(-x-y)(x+y) C.(x-y)(-x+y) D.(x-y-z)(-x+y+z)
下列各式相乘时,可以利用平方差公式的是 A.(-x-y)(x-y) B.(-x-y)(x+y) C.(x-y)(-x+y) D.(x-y-z)(-x+y+z)

(-x-y)(x-y)
=-(x+y)(x-y)
=-(x^2-y^2)
=y^2-x^2