Q34 / 100 · NTA Abhyas (JEE Main) 2020 · Mathematics · Vector Algebra

If a line passing through -2,1,α and 4,1,2 is perpendicular to the vector 3i^-4j^+5k^ and parallel to the plane containing vectors i^+2βk^ and 2βj^+αk^ ∀β≠0, then 10α+β is equal to

  • Correct answer
    A
    53
  • B
    54
  • C
    55
  • D
    56

Solution

Let, coordinates of A,B are respectively -2,1,α,4,1,2 respectively
AB→=6i^+2-αk^
∵AB→ is perpendicular to 3i^-4j^+5k^
⇒18+52-α=0⇒α=285
Also, AB→,i^+2βk^,2βj^+αk^ are coplanar
⇒602-α102β02βα=0
⇒2β12β+α-2=0⇒β=0 or 12β=2-α
12β=2-285
12β=-185⇒β=-310
 

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

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