Question

Find the sum of the first 22 terms of the AP 4,8,12
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Answer 1

${\huge{\underline{\sf {Answer}}}}$

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$\boxed{ {S}_{n} = 1012 }$

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${\huge{\underline{\sf {Explanation : }}}}$

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Given :

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AP = 4, 8, 12, ........

First term (a) = 4

Common Difference (d) = (8 - 4) = 4

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To find :

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Sum of first 22 terms of the AP

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Solution :

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Formula for sum of n terms :

$\sf \: {S }_{n} = \frac{n}{2} [2a + (n - 1)d]$

Where,

n = No. of terms

a = First term

d = Common difference

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Using the formula :

$\sf \: {S }_{22} = \frac{22}{2} [ 2(4) + (22 - 1)4]$

↬ $\sf \: {S }_{22} = 11 [ \: 8 + (21 \times 4) \: ]$

↬ $\sf \: {S }_{22} = 11(8 + 84)$

↬ $\sf \: {S }_{22} = 11 \times 92$

↬ $\sf \: {S }_{22} = 1012$

Answer 2

Hope this solution may help you...