Question

let there be an A.P with first term a and common difference d if there are m terms in the A.P then nth term is equal to​

Answer 1

Answer:

Since an=4

a+(n-1)2=4 given d=2

a+2n=6 ...........(1 )

Sn=-14

n/2{2a+(n-1)2}=-14

n{a+n-1}=-14

n(6-2n+n-1)=-14 from 1 a=6-2n

n(5-n)=-14

5n-n^2=-14

n^2-5n-14=0

n^2-7n+2n-14=0

n(n-7)+2(n-7)=0

(n-7)(n+2)=0

n=7 n=-2

Using this value in equation (1)

a=-8 & a=10