\({1\over2}+{3\over4}+{5\over8}+\ ...\infty\) का मान क्या है?

  1. 1
  2. 2
  3. 3
  4. 4

Answer (Detailed Solution Below)

Option 3 : 3
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Detailed Solution

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अवधारणा:

समान्तर-ज्यामितीय श्रेणी (AGP):

  • एक समान्तर-ज्यामितीय श्रेणी के पहले कुछ पद पहले पद a और सार्व अंतर d के साथ समान्तर श्रेणी से और पहले पद b और सार्व अनुपात r के साथ एक ज्यामितीय श्रेणी से बने हैं जिसे इसके द्वारा दिया जाता है:

    ab, (a + d)br, (a + 2d)br2, ... [a + (n - 1)d]brn - 1, ...

  • एक AGP के अनंत का योग, जिसका |r| ≤ 1, निम्न द्वारा दिया गया है:

    S = \(\rm{ab\over1\ -\ r}\ +\ {dbr\over(1\ -\ r)^2}\)

गणना:

दी गई श्रृंखला \({1\over2}+{3\over4}+{5\over8}+\ ...\infty\) एक AGP है जिसमें

a = 1, d = 2 और b = \(1\over2\) , r = \(1\over2\)

S = \(\rm{1\left(1\over2\right)\over1-{1\over2}}+{(2)\left(1\over2\right)\left(1\over2\right)\over\left(1-{1\over2}\right)^2}\)

⇒ S∞  = 1 + \({1\over2}\over{1\over4}\)

⇒ S∞  = 1 + 2

⇒ S∞  3.

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