The sum of the 2nd term and the 7th term of an ap is 30.if its 15th term is 1 less than twice of its 8th term,find the a.p
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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
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
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