Question

find the sum to n terms of the sequence whose

An = 5 - 6n


Pls Help ​

Answer 1

$<b><u> <i> Heya!! </b></u> </i>$

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$<b><u> Arithmetic Progressions </b></u>$

=> An = 5 - 6n

=> A (n+1) = 5 - 6 ( n + 1 ) = -1 - 6n

Common Difference = -1 - 6n - 5 + 6n

•°• $<b> <u> Common Difference is -6 </b> </u>$

→ Put n = 1 , An = 5 - 6n , we will get

$<u> First term a = -1</u>$

•°• Sum of n terms :-

$= > sn = \frac{n}{2} (2a + (n - 1)d) \\ \\ = > sn = \frac{n}{2} (a + an) \\ = >\frac{n}{2} ( - 1 + 5 - 6n)$

=> n ( 2 - 3n ) ✔

°•° The sum of n terms is $<b> <u> n (2 - 3n) </b> </u>$


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