What is the cross product of #<-3, -1, 8 ># and #<2,-4, -9 >#?

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Answer 1 · 2016-08-17T13:01:08

#((41),(-11),(14))#

Let

#vec(u) = -3vec(i) - vec(j) + 8vec(k)#

#vec(v) = 2vec(i) - 4vec(j) - 9vec(k)#

# vec(u) xx vec(v) = [(vec(i),vec(j),vec(k)),(-3,-1,8),(2,-4,-9)]#

#= vec(i)[(-1,8),(-4,-9)] - vec(j)[(-3,8),(2,-9)] + vec(k)[(-3,-1),(2,-4)]#

#=vec(i)(9+32) - vec(j)(27-16) + vec(k)(12+2)#

#therefore vec(u)xxvec(v) = 41vec(i) - 11vec(j) + 14vec(k)#