Question

fine the sum of First 17 terms of the A.P:
1/5 -3/10 -4/5

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Answer 1

Solution

Given :-

• terms of A.P. , 1/5 , -3/10 , -4/5 _____17 terms.

Find :-

• Sum of 17 terms of A.P.

Explanation

Formula

$\dag\boxed{\red{\tt{\:S_{n}\:=\:\dfrac{2a+(n-1)d}{2}}}}$

Where,

• a = first terms = 1/5
• d = common Defference = (-3/10 - 1/5) = -2

So Now keep all above Values in Formula

==> S17 = [2×1/5 + (17-1)(-2)]/2

==> S17 = [ 2/5 - 32]/2

==> S17 = (2 - 160)/2

==> S17= -158/2

==> S17 = -79

Hence

• Sum of 17 terms will be = -79

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Note

• Common difference of series always be same , if we take difference between any two alternate terms.

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