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Re: Understand Basic Ax+Bx=C
Posted:
Jul 11, 2013 3:29 PM


> 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 xaxis.
(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



