Finding Domain and Range On a Graph???

Question

Please please explain this to me in steps (Step 1, step 2, etc.)

I'm terrible at math and I really need help so can you please explain this in a simple way?

Ok look at this graph: http://cache.eb.com/eb/image?id=67240

(This is just an example of what I'm doing in class)

I need to find the domain and range on a graph.

My math teacher says if the line has arrows then it goes on to infinity or negative infinity. But if it does not have arrows then it doesn't and stops at whatever number.

How do I know what number?

I'm so confused!

Please help me out!

Answer 1

Domain is all real numbers (positive and negative): This is the x-axis. The range is your y-axis. It is always positive.

Range is all positive real numbers and 0.

Domain : (-∞, ∞ )

Range [0,∞ )

Answer 2

There should be a point at which the lines touch at. For example, if the 2 parts of the parabola touched at , say, (4,3), and (-4,-3), then the parabola has to go through those points.

So the domain of this graph is = {x|x x>= 0}

range = {y|y y>=0}

Because the parabola starts at (0,0), so the domain and range are both all numbers more than 0. Or perhaps, you could put all real numbers?