Question

ももせ

この矢印のところの変換がよく分からないです。教えてください！！

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n
(4πt) = Σ (k² + k)
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1
k=1
n(n + 1)(2n+1)+n(n + 1)
¡n(n+1){(2n+1)+3}
1
1
6
n(n+1)(2n+4)= n(n+1)(n+2)

Answer 1

✨ Best Answer ✨

トムくま

(1/6)n(n+1)(2n+4)
= (1/6)n(n+1)×2(n+2)
= (1/6)×2×n(n+1)(n+2)
= (1/3)n(n+1)(n+2)