Q28 / 118 · NTA Abhyas (JEE Main) 2020 · Mathematics · Sequences and Series

Given α and β are the roots of the quadratic equation x2-4x+k=0 k≠0. If αβ, αβ2+α2β and α3+β3 are in geometric progression, then the value of k is equal to

  • A
    4
  • Correct answer
    B
    167
  • C
    37
  • D
    12

Solution

Here, α+β=4,αβ=k
αβ,αβ(α+β) and α+β3-3αβα+β are in G.P.
⇒4k2=k64-12k
⇒16k2=4k16-3k
⇒4k=16-3k
⇒7k=16
⇒k=167

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

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