Q43 / 100 · NTA Abhyas (JEE Main) 2020 · Mathematics · Vector Algebra

Let p^×q→×p^+p^⋅q→q→=x2+y2q→+14-4x-6yp^, where p^ and q→ are non-collinear vectors ( p^ is a unit vector) and x, y are scalars, then the value of x2+y2 is equal to

  • A
    10
  • B
    11
  • C
    12
  • Correct answer
    D
    13

Solution

p^×q→×p^+p^⋅q→q→=x2+y2q→+14-4x-6yp^
p^2q→-p^⋅q→p^+p^⋅q→q→=x2+y2q→+14-4x-6yp^
Comparing both sides, we get, 
14-4x-6y=-p^⋅q→
x2+y2=1+p^⋅q→
x2+y2-4x-6y+14=1
x2+y2-4x-6y+13=0
x-22+y-32=0⇒x=2, y=3

Hence, the correct answer is option: 'D'.

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