The 5th and 11th term of an A.P. are 41 and 20 respectivelyFind the f – InterviewSolution

1.

The 5th and 11th term of an A.P. are 41 and 20 respectivelyFind the first term and sum of first 12 terms of the series

Answer»

a+4d=41a+10d=20

a+10d-a-4d=41-206d=21d=3.5a+14=41so a=27S12=12/2(2a+11d)=6(54+38.5)=555

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