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Let  R, a  = k ˆ 3 j ˆ 2 i ˆ    , b  = k ˆ 2 j ˆ i ˆ    If (( a  + b  )×( a  × b  )) × ( a  – b  ) = k ˆ 24 j ˆ 40 i ˆ 8   then |  ( a  + b  ) × ( a  – b  )| 2 is equal to

1. 132
2. 136
3. 140
4. 144

Correct answer: 140

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