13" y "" Af in "2N" AP "a=1,+n=20dSn=399" then "nig

In an AP, if a = 1 , a_(n)= 20 and S_(n) = 399 , then n is equal to

In an AP, if a = 1 , a_(n)= 20 and S_(n) = 399 , then n is equal to

In an A.P., if a = 1 , a_(n) = 20 and S_(n) = 399 , then n = ……..

Choose the correct alternative answer: The first term of an A.P. is 1 and nth term is 20 . If S_n=399 , then n=?

The sum of an A.P. is 1 and the nth term is 20. If S_(n)=399 , then n=…..

If C(n+1,3)=4C(n,2) then n=

If sum of n terms in an A.P is ((5n^2)/2+(3n)/2) then find its 20th term

If the n^(t h) term of an A.P. is (2n+1), find the sum of first n terms of the A.P.

If the numbers (2n-1), (3n+2) and (6n-1) are in AP, find n and hence find these numbers.

If the sum of n terms of an AP is given by S_(n)=3n+2n^(2) then common difference of the AP is