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MHT CET202121 Sep 2021Evening ShiftMathematicsVector AlgebraActual

If a = i +2 j -3 k , b =3 i + j +2 k , c = i +3 j + k and a + b is perpendicular to c , then =

Options

  1. A-2
  2. B4
  3. C-4
  4. D2

Correct answer

A. -2

Step-by-step solution

aligned & a + b =( i +2 j -3 k )+ (3 i - j +2 k ) & =(1+3 ) i +(2- ) j +(-3+2 ) k aligned Since a + b is er to c , we write aligned & (1)(1+3 )+(3)(2- )+(1)(-3+2 ) & 1+3 +6-3 -3+2 =0 =-2 aligned

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