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COMEDK2013MathematicsVector Algebra

( a i ) i +( a j ) j +( a k ) k is equal to

Options

  1. Aa
  2. B2 a
  3. C3 a
  4. D0

Correct answer

A. a

Step-by-step solution

Let a =x i +y j +z k , then ( a i )+(a j ) j +( a k ) k =[(x i +y j +z k i ] i +[(x i +y j +z k ) j ] j + [(x i +y j +z k ) k ] k =(x) i +(y) j +(z) k =x i +y i + k = a

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