Math, asked by vinayakrathod13, 2 months ago

एका अंकगणितीय श्रेढीचे 9 वे पद 18 आहे 4 थ्या व 7 व्या पदांची बेरीज 24 आहे. तर ती श्रेढी काढा ​

Answers

Answered by amitnrw
18

Given : एका अंकगणितीय श्रेढीचे 9 वे पद 18 आहे 4 थ्या व 7 व्या पदांची बेरीज 24 आहे.

The 9th term of an arithmetic series is 18 and the sum of the 4th and 7th terms is 24

To Find : श्रेढी

Series

Solution:

AP is  

a  , a + d , a + 2d , .. ..  ..  ..

aₙ = a + (n - 1)d

Sₙ = (n/2)(2a + (n-1)d)

a₉  = a  + 8d  = 18

a₄  = a + 3d

a₇ = a + 6d

a₄ +  a₇  = 24

=> a + 3d + a + 6d = 24

=> 2a + 9d  = 24

a  + 8d  = 18

2a + 9d  = 24

=> 7d  = 12

=> d = 12/7

a + 8(12/7) = 18

=> a = 30/7

Series is

30/7   ,  42/7  ,  54/7  ,  66/7  ,  78/7  , 90/7  ,  102/7  ,  114/7 ,  126/7 ...

=> 30/7   ,  6   ,  54/7  ,  66/7  ,  78/7  , 90/7  ,  102/7  ,  114/7 ,  18  ...

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Answered by Anonymous
0

Answer:

a  , a + d , a + 2d , .. ..  ..  ..

aₙ = a + (n - 1)d

Sₙ = (n/2)(2a + (n-1)d)

a₉  = a  + 8d  = 18

a₄  = a + 3d

a₇ = a + 6d

a₄ +  a₇  = 24

=> a + 3d + a + 6d = 24

=> 2a + 9d  = 24

a  + 8d  = 18

2a + 9d  = 24

=> 7d  = 12

=> d = 12/7

a + 8(12/7) = 18

=> a = 30/7

Step-by-step explanation:

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