A) \[24\mathbf{i}+7\mathbf{j}-5\mathbf{k}\]
B) \[7\mathbf{i}-24\mathbf{j}+5\mathbf{k}\]
C) \[12\mathbf{i}+3\mathbf{j}-5\mathbf{k}\]
D) \[\mathbf{i}+\mathbf{j}-7\mathbf{k}\]
Correct Answer: A
Solution :
\[(\mathbf{a}\times \mathbf{b})\times \mathbf{c}=(\mathbf{a}\,.\,\mathbf{c})\,\mathbf{b}-(\mathbf{b}\,.\,\mathbf{c})\,\mathbf{a}\] \[=(3+2+4)(2\mathbf{i}+\mathbf{j}-\mathbf{k})-(2-2-2)(3\mathbf{i}-\mathbf{j}+2\mathbf{k})\] \[=18\mathbf{i}+9\mathbf{j}-9\mathbf{k}+6\mathbf{i}-2\mathbf{j}+4\mathbf{k}\]\[=24\mathbf{i}+7\mathbf{j}-5\mathbf{k}\].You need to login to perform this action.
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