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If a =2 i + j +2 k , then the value of | i ( a i )|^2+| j ( a j )|^2+| k ( a k )|^2 is equal to

Options

  1. A17
  2. B18
  3. C19
  4. D20

Correct answer

B. 18

Step-by-step solution

i ( a i )=( i i ) a -( i a ) i = j +2 k aligned & Similarly, j ( a j )=2 i +2 k & k ( a k )=2 i + j & | j +2 k |^2+|2 i +2 k |^2+|2 i + j |^2 & =5+8+5=18 aligned

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