Heather was asked to graph 3x - y = -4 by using slope and y-intercept. Her graph is shown.

Answer 1

1. Since the equation is in standard form ax+ by = c you can solve this without rearranging.

a.) Slope, m= -a/b

b.) find your y-intercept by substituting x= 0 into the originally equation and solve for y. Your y-intercept is where it crosses the Y axis. Therefore X will equal zero.

a) -a/b = -3/-1=3 To use the is slope right it as a fraction 3/1.

b) 3(0) -y= -4

-y=-4. Divide by -1.

y=4

This gives the point

(0,4)

2) plot your Y intercept (0,4)

Then from the y-intercept use your slope 3/1 to rise 3and go to the right 1 and plot a point where you stop. Then you simply connect these two points with a line with arrows on each end.

Answer 2

 3x - y = -4 by using slope and y-intercept

First, rearrange the about equation to slope intercept form y=mx+b , m will be the slope(rise over run, and b will be your y intercept (0,h). the y intercept is the point the line crosses the y axis.

3x - y=-4

-y=-3x -4 here we are close, but lets get rid of all the negative signs by multiplying both sides by -1

y=3x + 4 now this looks like y=mx + b

1. Now we have a slope m = 3 ( can also be written 3/1 so it it easier to see rise over run), and a y intercept (0,4)
2. This is all you need to graph. start at the point (0,4) and count up 3 over 1, for the second point. From there you can plot another point , start at the second point and count up 3 and over 1.
3. Lastly, you can insert your points back into the original equation and see if it is a true statement.
4. 3x -y = -4 insert 0 for x and 4 for y 3(0) - 4 = -4 -4=-4 this is true!