Find the sum of first 35 terms of the series whose pth term is p/7+2
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8
a₁ = (1/7) + 2 = 15/7
a₂ = (2/7) + 2= 16/7
a₃ = (3/7) + 2 = 17/7
a₃₅ = (35/7) + 2
a₃₅ = 49/7
⇒ 35/2 {15/7 + 49/7}
⇒ 35/2 (64/7)
⇒ 160
∴ The sum of first 35 terms of the series whose pth term is p/7+2 is 160
a₂ = (2/7) + 2= 16/7
a₃ = (3/7) + 2 = 17/7
a₃₅ = (35/7) + 2
a₃₅ = 49/7
⇒ 35/2 {15/7 + 49/7}
⇒ 35/2 (64/7)
⇒ 160
∴ The sum of first 35 terms of the series whose pth term is p/7+2 is 160
Answered by
2
HI !
pth term is given by p/7 + 2
apply this to find the terms of the A.P :-
a₁ = (1/7) + 2 = 1 + 14/7 = 15/7
a₂ = (2/7) + 2= 2 + 14/7 = 16/7
a₃ = (3/7) + 2 = 3 + 14/7 = 17/7
The A.P is 15/7,16/7,17/7 .......
a = 15/7 , d = 1/7
35th term = a₃₅
a₃₅ = (35/7) + 2
= 49/7
Sn = n/2(a + an)
an = last term = 35th term of the A.P
S₃₅ = (35/2 {15/7 + 49/7}
= 35/2*64/7
= 160
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