What is the cross product of #[1,-2,-1]# and #[0, -1, 1] #?

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Answer 1 · 2017-10-28T08:23:37

#-3hati+hatj-hatk#

#[1,-2,-1]xx[0,-1,1]#

can be calculated by the determinate

#|(hati,hatj,hatk),(1,-2,-1),(0,-1,1)|#

expanding

#hati|(-2,-1),(-1,1)|-hatj|(1,-1),(0,1)|+hatk|(1,-2),(0,-1)|#

#=hati(-2 - 1)+hatj(1-0)+hatk(-1-0)#

#=-3hati+hatj-hatk#