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Question
What is the sum of the series 3−5−13...−229?
What is the sum of the series 3−5−13...−229?
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Solution
The correct option is C −3390
Given series is 3−5−13...−229It is an AP, with a=3 and d=−8 and l=−229We know l=a+(n−1)d⇒−229=3−8(n−1)⇒n=30Number of terms n=30
The sum of AP = n2(a+l)
=302(3−229)
=15×(−226)=−3390
Given series is 3−5−13...−229
It is an AP, with a=3 and d=−8 and l=−229
We know l=a+(n−1)d
⇒−229=3−8(n−1)
⇒n=30
Number of terms n=30
The sum of AP = n2(a+l)
=302(3−229)
=15×(−226)=−3390
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