The sum of the 5th & 9th terms of an AP is 40 & the sum of the 8th & 14th
terms is 64. Find the sum of the first 20 terms.
Answers
Answered by
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2a + 12d = 40
a + 6d = 20
Another equation
2a + 20d = 64
a + 10d = 32
From subtracting both the equation
We will get
d = 3
a = 2
Last term = 2 + 19×3
= 59
Sum of 20 terms will be
10 ( 2 + 59)
= 610
Answer
610
Hope This would help :)
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