श्रेणी 5, 7, 9..............के कितने पदों का योग 1020 होगा।'
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Step-by-step explanation:
a=5
d=7-5=2
Sn=1020
Sn=n/2[2a+(n-1)d]
1020=n/2[2*5+(n-1)2]
1020=n/2[10+2n-2]
1020=n/2(8+2n)
2n^2-2n+1020=0
n^2-n+520=0
(n-1)(n-520)
n=1 or n=520
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