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# Curious

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Why in  n(n+1)/2 do you divide by 2

Dec 1, 2019

#1
+700
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you divide by 2 because the 2 is in your denominator therefore it is a fraction......
for example 5 divided by 2 could also be seen as 5 TIMES 1/2 :)

hope this helps in some way.

Dec 1, 2019
#2
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I'm going to answer the same, just with slightly different words.

A fraction line, which is shown as / here, is exactly the same thing as a divide by sign.

For instance.

$$\frac{9}{2}=4\frac{1}{2}\\ 9\div 2 = 4\frac{1}{2}\\$$

See how the divide by sign looks like a fraction, only it has dots top and bottom instead of numbers?

Well, that is no coincidence.

Dec 1, 2019
#3
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I've noticed in this problem there is a person icon in the corner...

Dec 1, 2019
#4
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Hi Tom,

I really don't know. I don't remember seeing that symbol before.

I think it has been labelled as a high priority question. Maybe it is advertised in FaceBook or somewhere else.

It is bordered top an bottom by a heavy line in the question list.

GingerAle  is the one most likely to be able to answer your question.

Melody  Dec 1, 2019
edited by Melody  Dec 1, 2019
#5
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Thank you!

tommarvoloriddle  Dec 1, 2019
#13
+700
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i think it just means moderator? :)

oh wait! you were referring to something else LOL!

Nirvana  Dec 3, 2019
edited by Nirvana  Dec 3, 2019
#6
+9475
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Maybe Guest is referring to this:

$$\sum\limits_{k=1}^{n}k\ =\ \frac{n(n+1)}{2}$$

in which case, the following might help:

Dec 1, 2019
#7
+118653
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mmm maybe.

Hi Hectictar!

Melody  Dec 1, 2019
#8
+1

I believe hectictar is right!. I think he/she means that when you are summing up  a sequence of numbers, say from 1 to 10, why do you do this: [10 x (10+1)] / 2 = 55.

Guest Dec 1, 2019
#9
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omg hecticar the 1+6 2+5 3+4 etc explanation

nobody ever showed it to me that way before

it's so obvious now ... i'm so happy i'm crying

Guest Dec 1, 2019
#10
+2

Thank you so much Hectictar. I've never thought about it like that

Guest Dec 1, 2019
#11
+9475
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Glad it helped!! I learned it from one of my professors!

Also, Hi Melody!

hectictar  Dec 1, 2019
#12
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what are you studying?

Guest Dec 1, 2019