How do you graph #3x-y=9# using intercepts?

2 Answers
Oct 9, 2017

Answer:

Get the y-intercept and x-intercept, then draw a continuous and linear line across the y and x-intercept.

Explanation:

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 #3x# from both sides so we get something like #-y=-3x+9#.

Now to fully isolate y, we divide both sides by -1 (or multiply). If we do we get something like #y=3x-9#.

Now, we can get the y-intercept by plugging in 0 for x so we get something like...#y=3(0)-9#. Or #y=0-9#. We now know the y-intercept is #-9#.

To find the x-intercept, we make y equal 0 so we get something like #0=3x-9#. Now our job is to find what x is by isolating it. So we first add both sides by 9...

#9=3x#, then we divide both sides by 3.

#x=3#.

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)

Oct 9, 2017

Answer:

x-intercept = 3 & y-intercept = -9.

Explanation:

#y=3x-9#
It is in the form #y=max+c# where c is the y-intercept.
#:.#y-intercept = -9.
When #y=0#,
#0=3x-9# or #x=3# or 3 is the x-intercept