Gujarati
8. Sequences and Series
easy

यदि समान्तर श्रेणी के $n$ पदों का योग $3{n^2} + 5n$ व ${T_m} = 164$ हो, तो  $m = $

A

$26$

B

$27$

C

$28$

D

इनमें से कोई नहीं

Solution

(b) स्पष्टत:,

$164 = (3{m^2} + 5m) – \{ 3{(m – 1)^2} + 5(m – 1)\} $

$= (3{m^2} + 5m) – 3{m^2} + 6m – 3 – 5m + 5$

$ \Rightarrow $  $164 = 6m + 2$

$ \Rightarrow $$m = 27$.

Standard 11
Mathematics

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