How do you graph #3x-y=9# using intercepts?
Get the y-intercept and x-intercept, then draw a continuous and linear line across the y and x-intercept.
We are able to draw a linear line across the y-intercept and x-intercept because we know it's a linear line a.k.a. the slope never changes.
So since we know this, we should firstly isolate the y. First we subtract
Now to fully isolate y, we divide both sides by -1 (or multiply). If we do we get something like
Now, we can get the y-intercept by plugging in 0 for x so we get something like...
To find the x-intercept, we make y equal 0 so we get something like
Now we know the x and y-intercepts, we just plot them on the graph, and draw a straight line through both of the points and that's how we graph the whole line!
If you're still not sure about this, plug in any x-value and you should get the y-value that matches the graph. (provided that you drew straight enough)