How many terms of an AP 9,17,25,......must be taken to give a sum of 636
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Apologies 9,17,25,......
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a= 9 ,d= 8..
Sn = n/2{2a+ (n-1)d}
636= n/2{2×9 +( n-1)8}
1272= n (18+8n-8)
1272= 8n^2+10n
636= 4n^2+5n
0 = 4n^2+5n-636
by splitting method,
4n^2+ 48n -53n -636
4n(n+14)-53(n+14)
(n+14)(4n-53).
n = -14, 53.
But n can not be negative so,
n = 53..
I hope it help you....☺️☺️☺️
Sn = n/2{2a+ (n-1)d}
636= n/2{2×9 +( n-1)8}
1272= n (18+8n-8)
1272= 8n^2+10n
636= 4n^2+5n
0 = 4n^2+5n-636
by splitting method,
4n^2+ 48n -53n -636
4n(n+14)-53(n+14)
(n+14)(4n-53).
n = -14, 53.
But n can not be negative so,
n = 53..
I hope it help you....☺️☺️☺️
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