Q21 of 89 Page 51

Find the sum

First term,


Common difference,


No of terms, n = 11


Sum of first n terms,







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21

Find the sum

1 + (–2) + (–5) + (–8) + …+ (–236)

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Find the sum

 22

Which term of the AP – 2, - 7, - 12, … will be - 77? Find the sum of this AP upto the term - 77.

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If an = 3 – 4n, then show that a1, a2, a3, … from an AP. Also, find S20.