Summation Notation

2 Questions


I was looking back through the lecture notes for Chapter 2, examples 16 and 16.5. I was wondering, why when it asks in example 16, (∑xi)², you add whats in the set and then square the sum. But when it asks in example 16.5, is ∑(xi-3)², you square each sum in the set, and then add it all together?

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I'm working on the homework in section 2.2, question 16. The first part of the question asks for the summation of the set (7,9,2,-1, and 3) with x(i)-4, and the second part of the question asking for (x(i)-4). I keep getting the answer of 0 for the first part of the question, and the homework says that 0 is the answer for the second part of the question, but I'm not understanding the differences between the two parts of the question, or how to solve them.

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