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JEE Mains · Maths · STD 11 - 8. sequence and series

જો \(a _{1}(>0), a _{2}, a _{3}, a _{4}, a _{5}\) સમગુણોતર શ્રેણીમાં હોય, \(a _{2}+ a _{4}=2 a _{3}+1\) અને \(3 a _{2}+ a _{3}=2 a _{4}\),હોય તો,\(a _{2}+ a _{4}+2 a _{5}=\dots\dots\dots\) 

  1. A \(30\)
  2. B \(20\)
  3. C \(30\)
  4. D \(40\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(40\)

Step-by-step Solution

Detailed explanation

\(a _{1}>0, a _{2}, a _{3}, a _{4}, a _{5} \rightarrow G \cdot P .\) \(3 a _{2}+ a _{3}=2 a _{4}\) \(3 ar + ar ^{2}=2 ar ^{3}\) \(3+ r =2 r ^{2}\) \(2 r ^{2}- r -3=0\) \(r =-1\) and \(r =\frac{3}{2}\) \(a _{2}+ a _{4}=2 a _{3}+1\) \(ar + ar ^{3}=2 ar ^{2}+1\)…
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