Question

2) Find the sum of the series upto 30 terms :
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Answer 1

Answer:

It is given that the terms are in arithmetic sequence. Therefore, the sum of the first 30 terms is 3225.

Answer 2

Answer:

Here the Series is =(1−50)+(4−45)+(7−40)+...(30 terms)

=−49−41−33....(15 terms)

Difference d=−41−(−49)=−33−(−41)=8

Sum, S

n

=

2

n

[2a+(n−1)d]

Since the series is made by combining two terms (i.e, (1−50),(4−45)...) therefore we will have to take the sum of the first 15 terms for the newly formed series to get the sum of first 30 terms of the given series.

∴S

15

=

2

15

[2×(−49)+(15−1)(8)]=105

Step-by-step explanation:

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