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MHT CET202311 May 2023Evening ShiftMathematicsVector AlgebraActual

If a = i +4 j +2 k , b =3 i -2 j +7 k , c =2 i - j +4 k , then a vector d which is parallel to vector a b and which c d =15 , is

Options

  1. A30 i - j -14 k
  2. B90 i -3 j -42 k
  3. C90 i + j -7 k
  4. D30 i -3 j +7 k

Correct answer

B. 90 i -3 j -42 k

Step-by-step solution

Here, c =2 i - j +4 k And given that c d =15 We verify given options one by one to satisfy the above condition. Consider option (B), For d =90 i -3 j -42 k aligned c d & =(2)(90)+(-1)(-3)+(4)(-42) & =180+3-168=15 aligned Option (B) is correct.

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