Question

if nth term of an A.P is 4,d=2 and sum of n terms is -14 find n and a​

Answer 1

Step-by-step explanation:

nth term = 4

Difference, d = 2

Sn = -14

We know,

Sn = n/2(a+l)

-14 = n/2(a+4)

(-28 - 4n)/n = a   ...................(1)

We know,

an = a + (n-1)d

4n = -30 - 4n + 2n^2

n^2 - 4n - 15 = 0

solve futher to get answer......................