The sum of first 11 terms of an ap is 19 and the sum of first 19 terms is 11.Find the sum of 30 terms
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Answered by
3
Answer:
0
Step-by-step explanation:
Use the formula to find sum of AP up to n terms
where a is the first term, d is the common difference, n is the number of terms.
So, 11/2(2a+10d) = 19/2(2a+18d)
22a+110d=38a+342d
16a=-232d
a=-14.5d
Now sum of first 30 terms
=30/2(2a+29d)
=15(29d- 29d) = 0
.
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Answered by
11
Answer:
Step-by-step explanation:
Answer is -30
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