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  • 1 Post By romsek
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December 3rd, 2016, 01:52 AM   #1
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From: Mars

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Class has gotten to me. I can't get a hold of my teacher over the weekend so I'm hoping you guys can understand my question.

There is this equation: $\displaystyle \sum c^2 = \left ( 1 \right )^{2} + \left ( -1 \right )^{2}$ that I don't understand why the second one is negative. Each number is supposed to represent a group. So if I were to compare one group to two groups I would should do this equation: $\displaystyle \sum c^2 = \left ( 1 \right )^{2} + \left (\frac{1}{2} \right )^{2} + \left (\frac{1}{2} \right )^{2}$

Why is the negative number there? I get the feeling that the question is out of context, let me know what you need from me to clarify.
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December 3rd, 2016, 11:21 AM   #2
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if I saw

$\sum c^2 = (1)^2 + (-1)^2$

my immediate interpretation would be that

$c \in \{1,~-1\}$

without further context I don't know what we can tell you.
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December 4th, 2016, 01:59 AM   #3
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It's for psychology. The first equation is based on two groups of people only. The second equation is one group being compared to two groups.
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