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In an A.P., 1^(st) terms is 1 and the la...

In an A.P., `1^(st)` terms is 1 and the last term is 20. The sum of all terms is 399 then n = …………. A)42 B)38 C)21 D)19

A

42

B

38

C

21

D

19

Text Solution

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The correct Answer is:
B
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