如何计算(x-2y+3z)(x+2y-3z)?

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如何计算(x-2y+3z)(x+2y-3z)?

如何计算(x-2y+3z)(x+2y-3z)?
如何计算(x-2y+3z)(x+2y-3z)?

如何计算(x-2y+3z)(x+2y-3z)?
(x-2y+3z)(x+2y-3z)
=[x-(2y-3z][x+(2y-3z)]
=x^2-(2y-3z)^2
=x^2-(4y^2-12yz+9z^2)
=x^2-4y^2-9z^2+12yz

(x-(2y-3z))(x+2y-3z)=x2-(2y-3z)2

原式=-(-x+2y-3z)(x+2y-3z)=-[(2y-3z)^2-x^2]=

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