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KCET2018MathematicsVector Algebra

If ( | a | ) and ( | b | ) are mutually perpendicular unit vectors, then ( (3| a |+2| b |) (5| a |-6| b |)= )

Options

  1. A5
  2. B( 03 )
  3. C( 06 )
  4. D( 12 )

Correct answer

B. ( 03 )

Step-by-step solution

Given that, (3 a +2 b ) (5 a -6 b ) Since, a b =0 and | a |=| b |=3 Then (3 a +2 b ) (5 a -6 b )=15| a |²-18(0)+10(0)-12| b |²=3

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