\(A=a\left(bz-cy\right)+b\left(cx-az\right)+c\left(ay-bx\right)\)
\(A=abz-acy+bcx-baz+cay-cbx\)
\(A=\left(abz-baz\right)-\left(acy-cay\right)+\left(bcx-cbx\right)\)
\(A=z\left(ab-ba\right)-y\left(ac-ca\right)+x\left(bc-cb\right)\)
\(A=z.0-y.0+x.0=0\)
Vậy A = 0