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

ધારો કે \(\mathrm{a}_{\mathrm{n}}\) એ સમાંતર શ્રેણીનું \(\mathrm{n}^{\text {th }}\) પદ છે.
જો \(S_n=a_1+a_2+a_3+\ldots+a_n=700, a_6=7\) અને \(S_7=7\) હોય, તો \(\mathrm{a}_{\mathrm{n}}\) = __________

  1. A 56
  2. B 65
  3. C 64
  4. D 70
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Answer & Solution

Correct Answer

(C) 64

Step-by-step Solution

Detailed explanation

\(\mathrm{S}_{\mathrm{n}}=700=\frac{\mathrm{n}}{2}[2 \mathrm{a}+(\mathrm{n}-1) \mathrm{d}]\)...(i) \(a_6=7 \Rightarrow a+5 d=7\)...(ii) \(\mathrm{S}_7=7 \Rightarrow \frac{7}{2}(2 \mathrm{a}+6 \mathrm{~d})=7\) \(a+3 d=1\)...(iii) (ii) અને (iii) ઉકેલતા,…
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