怎么计算:1.(x-2y+z)(-x+2y+z) 2.(2x-3y-1)(2x+3y-1)

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怎么计算:1.(x-2y+z)(-x+2y+z) 2.(2x-3y-1)(2x+3y-1)

怎么计算:1.(x-2y+z)(-x+2y+z) 2.(2x-3y-1)(2x+3y-1)
怎么计算:1.(x-2y+z)(-x+2y+z) 2.(2x-3y-1)(2x+3y-1)

怎么计算:1.(x-2y+z)(-x+2y+z) 2.(2x-3y-1)(2x+3y-1)
(x-2y+z)(-x+2y+z)
=(z+x-2y)(z-(x-2y))
=z^2-(x-2y)^2
=z^2-x^2+4xy-4y^2
(2x+3y-1)(2x-3y+1)
=[2x+(3y-1)][2x-(3y-1)]
=(2x)^2-(3y-1)^2
=4x^2-(9y^2-6y+1)
=4x^2-9y^2+6y-1

  1. 原式=(z+x-2y)(z-x+2y)=z^2-(x-2y)^2=z^2-x^2+4xy-4y^2

  2. 原式=(2x-1-3y)(2x-1+3y)=(2x-1)^2-9y^2=4x^2-4x-9y^2+1