please solve the 5th question ........?
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Given S1 = 6
This means the first term
S7 = 7/2 { 12 + 6*d } = 105 (given)
==> 6 d = 18
Or d = 3
Hence Sn = n/2 { 12 + (n-1) 3} = n/2 * (3n +9) = n/2 * 3(n+3)
And Sn-3 = (n-3)/2 {12 + (n -4) 3} = (n-3)/2 * 3n
Sn/Sn-3 = (n+3)/(n-3)
or
(n+3):(n-3)
hope helps....give ur feedback in the cmmt box
:-)
This means the first term
S7 = 7/2 { 12 + 6*d } = 105 (given)
==> 6 d = 18
Or d = 3
Hence Sn = n/2 { 12 + (n-1) 3} = n/2 * (3n +9) = n/2 * 3(n+3)
And Sn-3 = (n-3)/2 {12 + (n -4) 3} = (n-3)/2 * 3n
Sn/Sn-3 = (n+3)/(n-3)
or
(n+3):(n-3)
hope helps....give ur feedback in the cmmt box
:-)
tejaswini95:
welcome
and thanks for the answer
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