Q32 / 75 · JEE Main 2020 (07 Jan Shift 1) · Mathematics

Let α and β be two real roots of the equation k+1tan2x-2⋅λtan⁡x=1-k, where k≠-1 and λ are real numbers. If tan2α+β=50, then a value of λ is

  • A
    102
  • Correct answer
    B
    10
  • C
    5
  • D
    52

Solution

k+1tan2⁡x-2λtan⁡x+k-1=0
tan⁡α+tan⁡β=2λk+1
tanαtan⁡β=k-1k+1
tan⁡α+β=2λk+11-k-1k+1=2λ2=λ2
tan2⁡α+β=λ22=50
λ=±10

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

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