If the sum of the first ten terms of the series 1 5 + 2 65 + 3 325 + 4 1025 + 5 2501 + … . is m n ,…

If the sum of the first ten terms of the series 15+265+3325+41025+52501+. is mn, where m and n are co-prime numbers, then m+n is equal to ______.

Solution

For the series 15+265+3325+41025+52501+

Tn=n4n4+1

=n2n2+12-(2n)2=n2n2+2n+12n2-2n+1

=1412n2-2n+1-12n2+2n+1

Now S10=n=110 Tn=n=1101412n2-2n+1-12n2+2n+1

=1411-15+15-113+113+1181-1221

=141-1221=55221=mn

Hence, m+n=55+221=276

Asked in: JEE Main 2022 (27 Jun Shift 1)

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