Graph Help

You might like to put it in slope-intercept form:

. . . . y = mx + b

to find the slope m and the y-intercept b.
 
alexflury said:
You might like to put it in slope-intercept form:

. . . . y = mx + b

to find the slope m and the y-intercept b.
Click to expand...

How do I solve this problem? I tried but I'm a little lost.
 
Firstly, you make the equation look like "y = mx + b", where m and b are some constants. Have you tried to do that? What have you tried?
 
I plugged in the numbers to the formula. Why did I do something wrong?
 
y = mx + b

2y= -3x + b

I really don't know what I'm doing. I'm really lost here.
 
Where did that 2 come from? How do you know that m = -3?

Just take 2y + x = -3, and solve for y. Then you'll get "y = [something]", which is one step towards "y = mx + b".
 
When you look at "y = mx + b", you'll see that y is by itself on one side. So in order to get "2y + x = -3" in that form, we need to get y by itself on one side. First get the x on the other side by subtracting x from both sides.

. . . . 2y + x = -3
. . . . <==> (2y + x) - x = -3 - x
. . . . <==> 2y = -3 - x

Now what? We still need to get y by itself on one side.
 
Not a problem. If you tell me how you arrived at y = 5, I may be able to tell you where you went wrong, but if you're not interested, okay.

Anyway, we have:

. . . . 2y = -3 - x

and we're trying to make that look like:

. . . . y = mx + b

That doesn't have a "2" on the left, and our equation does. What do we need to do to both sides of our equation to get rid of the "2" on the left?
 
I found out what I did wrong.

What I have now is:

2y+3=-3
2y=-6
y= -3

(3, -3) is the point on the line.

and then

x= -3
2y -3 = -3
2y=0
y=0

(-3,0) is the other point on the line.
 
Okay, that's another way to do it. Now you can plot those two points and draw a line that joins them.

In case you're interested, here's the slope-intercept method.

2y + x = -3
<==> 2y = -x - 3
<==> y = -(1/2)x - 3/2

So m = -1/2 and b = -3/2.

The y-intercept is -3/2, so start at the point (0, -3/2). The slope is -1/2, so move up -1 and to the right 2 to find points to the right of the y-axis. Move up 1 and to the right -2 to find points to the left of the y-axis.
 
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