Question 81664: I can't seem to fully understand how to get through the whole process to the answer.
in the book the problem states as follows:
5y-3x=15
let y=0 5y-3x =15
5(0)-3x =15
-3x =15
x =15
let x=0 5y-3x =15
5y-3(0)=15
5y =15
y =3
let y=6 5(6)-3x =15
30-3x =15
-3x = - 15
- 15
x = -15/-3 or 5
okay, this is the example in the book. I don’t understand where the uses of the 6 as y comes in. Please help. thank you.
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! To specifically answer your question, when you are graphing points, you can use ANY value of either x or y that you want to use. It doesn't matter what you use. Usually we use x = 0 and find y, then we let y = 0, and find x. This is because these are the y and x-intercepts, which are the easiest and also the most important points to graph. HOWEVER, if you want a third point, then you can select ANY other value of x or y, substitute it in, and solve for the other variable.
I did notice that you have an error in the first part of your problem, but it's probably just that you miscopied it. Anyway, in the beginning, you said that you let y=0, and down from that a couple of steps you have
-3x =15
x =15
Of course, it should be x = -5, right??
R^2 at SCC
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