What is the slope and y-intercept of the line 9x+3y=12?

1 Answer
Jun 6, 2016

The slope is -3 and the y-intercept is 4.

Explanation:

It helps if you put your equation into the standard linear form of y=mx+b. In this form, m is always the slope, and b is always the y-intercept.

To get it into standard form, you need to isolate y. To do this, I can first move the 9x by subtracting it from each side of the equation, giving me:

3y = -9x + 12

Then, I would divide each side by 3, to isolate the y. The distributive property requires that both -9y and 12 be divided by 3 as well. This gives me:

y = -3x +4

Now I have my equation in standard form, and can see that the slope is -3 and the y-intercept is 4. That can be reflected by graphing the line as well: graph{-3x +4 [-4.834, 5.166, -0.54, 4.46]}