(X-Y-Z)的平方怎么算快.

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(X-Y-Z)的平方怎么算快.

(X-Y-Z)的平方怎么算快.
(X-Y-Z)的平方怎么算
快.

(X-Y-Z)的平方怎么算快.
(x-y-z)^2
=(x-y-z)(x-y-z)
=x^2+y^2+z^2-2xy-2xz+2yz

(X-Y-Z)^2
=(X-Y)^2-2(X-Y)Z+Z^2
=X^2-2XY+Y^2-2XZ+2YZ+Z^2

(x-y-z)^2
=(x-y-z)(x-y-z)
=x(x-y-z)-y(x-y-z)-z(x-y-z)
=x^2-xy-xz-xy+y2+yz-zx+zx+z2
=x^2+y^2+z^2-2xy-2yz-2zx