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MHT CET202013 Oct 2020Evening ShiftMathematicsVector AlgebraActual

a = i +j+ k , b = i -j+2 k and c =x|+(x-1) - k . If the vector c lies in the plane of u and b , then x=

Options

  1. A2 3
  2. B-3 2
  3. C-2 3
  4. D3 2

Correct answer

B. -3 2

Step-by-step solution

Given vectors are coplanar, we write : a ( b c )=0 aligned & | array ccc 1 & 1 & 1 1 & -1 & 2 x & x-1 & -1 array |=0 & 1(1-2 x+2)-1(-1-2 x)+1(x-1+x)=0 & 3-2 x+1+2 x+2 x-1=0 2 x+3=0 x= -3 2 aligned

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