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

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Correct answer: B. 18

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

BITSAT Mathematics Question (2024) — Solution

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