Let u=<−2,1,−1>,v=<−3,2,−1>,w=<1,3,5>.
Compute:
a) u×w=∣∣i−21j13k−15∣∣=i(1⋅5−(−1)⋅3)−j((−2)⋅5−(−1)⋅1)+k((−2)⋅3−1⋅1)=i(5+3)−j(−10+1)+k(−6−1)=<8;9;−7>
b)
u×(w×v)=∣∣i1−3j32k5−1∣∣=i(3⋅(−1)−5⋅2)−j(1⋅(−1)−5⋅(−3))+k(1⋅2−3⋅(−3))=i(−3−10)−j(−1+15)+k(2+9)=
=∣∣i−2−13j1−14k−111∣∣=i(1⋅11−(−1)⋅(−14))−j((−2)⋅11−(−1)⋅(−13))+k((−2)⋅(−14)−1⋅(−13))=i(11−14)−j(−22−13)+k(28+13)=<−3;35;41>
(u×w)×v=∣∣i−21j13k−15∣∣=i(1⋅5−(−1)⋅3)−j((−2)⋅5−(−1)⋅1)+k((−2)⋅3−1⋅1)=i(5+3)−j(−10+1)+k(−6−1)=∣∣i8−3j92k−7−1∣∣=i(9⋅(−1)−(−7)⋅2)−j(8⋅(−1)−(−7)⋅(−3))+k(8⋅2−9⋅(−3))=i(−9+14)−j(−8−21)+k(16+27)=<5;29;43>.
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