Question

find the sum of 2 n term of series=1^2-2^2+3^2-4^2+5^2-6^2+7^2​

Answer 1

Answer:n(n+1)\2, when N is even

Step-by-step explanation:

Case1

1^2-2^2. 3^2-4^2. N^2-n^2

=a^2-b^2. =a^2-b^2. A^2-b^2

(1-2)(1+2). (3-2)(3+2). (N-n)n-1

-1(1+2+3+4) n and N cancel ie , -1(n)

-1x n(n+1)\2 so, -n(n+1)\2, when N is even

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