Question

The sum of the first six terms of an ap is zero and the fourth term is 2.find the sum of its first 30 terms.

Answer 1

I hope it will help

Answer 2

Answer:

Step-by-step explanation:

let the sum of 30 terms be S30

'a' is first term

A4=2

S6=o

n/2[2a+5d]=0

2a+5d=0. . . . . . .(1)

a4=2

a+3d=2. . . . . . . . (2)

multiply by 1 for eqa(1)  ,2 by eqa (2)

2a+5d=0

2a+6d=4

(-)    (-)

d=4

substituding the value of d=4 in eqa 1

a+3(4)=2

=-10

a30=a+29d

     =-10+29(4)

     = 106

Sn=n/2[a+l]

S30=30/2[-10+106]

     =15(96)

     =1140