Question

find s10 of the A.P 41,36,31,26...
185
186
187
188​

Answer 1

QuEstion :

• Find the sum of first 10 terms of AP 41, 36 , 31 , 26...

AnswEr :

GivEn :

• first term = a = 41
• common diff. = d = - 5
• no. of times =n= 10

To find :

• $\bold{ s= ???}$

Formula used :

$\sf{\red{\boxed{\bold{S = \dfrac{n}{2}[ 2a + ( n - 1 ) d ]}}}}$

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• Substituting the values,

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: $\implies\: \sf {\bold{ S= \dfrac{10}{2}[ 2\times 41 + ( 10 - 1 ) -5}}$

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: $\sf\implies\:{\bold{ S = 5 [ 82 + 9 \times - 5 ]}}$

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: $\sf\implies\:{\bold{ S = 5 [ 82 - 45 ]}}$

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: $\sf\implies\:{\bold{S = 5 \times 37}}$

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:$\sf\implies\: {\bold{ S = 185 }}$

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${\bold{\green{\boxed{\boxed{\sf{ S = 185 =Option\: A }}}}}}$