Question

the sum of 2nd and 7th term of ap is30 if its 15th term is 1 less thn twice its 8th term find the Ap

Answer 1

comment if it's not clear

Answer 2

Here is your solution

Given:-

t2+t7=30
=>a+d+a+6d=30
=>2a+7d=30..................... (1)

A/q
15th term=2×8th term-1
=>a+14d=2×(a+7d)-1
=>a+14d=2a+14d-1
=>14d-14d+1=2a-a
=>1=a

Putting the value of a in equation (1)

2a×7d=30
2×1+7d=30
2+7d=30
7d=30-2
7d=28
d=4

A.p are a,a+d,a+2d,a+3d,a+4d

=>A.p are 1,5,9,13.........

HOPE IT HELPS YOU