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**mom****Member**- Registered: 2012-04-25
- Posts: 94

I have no idea why but I completely forgot how to do this one.

find the value of a such that the three points (1,3), (6,5), and (a,-1) lie on the same line.

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 87,258

Hi mom;

Use the point point equation for the first two points and then just solve for a. a = - 9.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**mom****Member**- Registered: 2012-04-25
- Posts: 94

Ok, thanks. No idea why it was throwing me off

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 87,258

You are welcome.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**DeanPemberton****Member**- From: USA
- Registered: Yesterday
- Posts: 9
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You use the formula of three points lying in the same line and find all the points of the line. First you have to find the slope of the line then find by equation of line "y-y1=m(x-x1). Then definitely you will get its answer.

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