Question

What is ∑n=17(10n+90) equal to?

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Answer 1

Answer:

910

Step-by-step explanation:

$\sum_{n=1}^{7}(10n+90)\\\\=\sum_{n=1}^{7}(10n)+\sum_{n=1}^{7}(90)\\\\=10\sum_{n=1}^{7}(n)+90(7)\\\\=10(\frac{7(7+1)}{2})+630\\\\=10(28)+630\\\\=280+630\\\\=910$