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Topic: Understand Basic Ax+Bx=C
Replies: 1   Last Post: Jul 11, 2013 3:29 PM

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Narasimham

Posts: 350
Registered: 9/16/06
Re: Understand Basic Ax+Bx=C
Posted: Jul 11, 2013 3:29 PM
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> Hello,
> I'm reading a book trying to catch up on my
> geometry.
> In the book I can't for the life of me figure out how
> the author devised some of the answers he's been
> giving.
>
> In the simple equation y=3 he converts it to Ax+Bx=C
> equaling 0x+1y=3. Earlier he stated that "The graph
> of an equation of the form Ax+By=C, where A and B are
> not both 0, is a straight line." A is 0 and the
> equation results in a straight line.
>
> In the second part of the problem he states:
> "Pick three x values, such as 0, 1, -1. When you plug
> them into the equation, you get the three ordered
> pairs (0,3), (4,3), and (-4,3)."
>
> How is it if you put 0, 1, and -1 as x you get
> anything that isn't 0, 1, and -1 as x. I have no idea
> how the answers 0, 4, and -4 were came up with.
>
> I'm totally confused I left the question and starting
> other problems. Appreciate any help that is offered.
> Thanks


If the author had written in the following way, you would perhaps have no problem understanding.
-----
The graph of an equation of the form A x + B y = C where A and B are not both 0, is a straight line inclined to x - axis.

If in the special case when A = 0, then y = C/B is a straight line parallel to x -axis. To show it graphically,pick three x values,no matter whatever they are, such as 0, 4, and -4 with corresponding y value always = 3.You get the three ordered pairs (0,3), (4,3), and (-4,3), which are the three points on a line above and parallel to x-axis.

(C/B) can be (3/1) or (6/2) or (360/120) or (12/4) etc. When you plug them into the equation, it is always satisfied.
------

HTH
Narasimham



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