# Need help

1. Jan 14, 2006

### Mt. Nixion

I am doing this worksheet where I have to graph the following,

1.

A. x=-3
B. y=-1
C. x-y=2
D.x+y=6

2.

A. y=x
B.y=-x
C.y=2x-6
D.y=-1/2x-6

I know you don't do the homework for other people, but could you show me how to do these please?

2. Jan 14, 2006

### HallsofIvy

Staff Emeritus
Here's the important hint: every one of those functions is linear. Each graph is a straight line. Two points determine a straight line. Determine the y value for two different values of x, plot the points, draw the line throught those two points.

For example, in 1c) when x= 1, the equation x-y= 2 becomes 1- y= 2. What is y? when x= 0, the equation becomes 0-y= 2. What is y?

Don't forget that an equation means exactly what it says. For 1b) the equation is y= -1 which doesn't have an x in it! When x= 0, what is y? When x= 1, what is y?

The one "hard" one is the very first: 1a) x= -3. Since you are told that x must be -3, it makes no sense to ask "if x= 0, what is y?" But you can do it the other way around: When y= 0, what is x? Plot that point. When y= 1, what is x? Plot that point. Draw the line through those points.

3. Jan 15, 2006

### Mt. Nixion

I do not quite understood what you said, HallsofIvy. Could you give some more detail or can anyone else help me?

4. Jan 15, 2006

### arildno

For ALL these exercises, you are to plot ALL points in the x,y-plane satisfying the given equation (ideally, that is).

Taking the first:
If you plot ALL points in the x,y-plane whose x-coordinates are all equal to -3 (that's what the equation requries), and no other points, what sort of curve do you end up with?

5. Jan 16, 2006

### HallsofIvy

Staff Emeritus
What DO you know how to do? Can you graph a single point?

Take a look at x- y= 2. When x= 0 what is y? Can you plot that point: (0, __)? When y= 0 what is x? Can you graph that point: (__, 0)?

If you can do that, draw the line through those two points.