# Thread: domain and range URGENT!!!!!!!

1. ## domain and range URGENT!!!!!!!

Find the domain and range of the function: f(x)=(4/5) l8-xl

2. Originally Posted by iheartthemusic29
Find the domain and range of the function: f(x)=(4/5) l8-xl
Domains are easy. What values of x does f(x) not exist? There are no restrictions here so the domain of the function is all real numbers.

Ranges are harder. When all else fails, graph it. In this case we can see that the minimum of the function is at x = 8. There is no upper bound. So the range is $[0, \infty )$.

-Dan

3. ## Ummmmm

I'm still confused. What does the 8 have to do with it? Where did the zero come from? Why is it infinity?

4. Why post again this?

Look at here

Dan gave you a full explanation.

5. because I didn't understand it!

6. Then you should've posted there, not to create another thread.

7. well I knew I had posted it it once before but I couldn't find it again! sorry! and I'm still not understanding it!

8. Originally Posted by iheartthemusic29
I'm still confused. What does the 8 have to do with it? Where did the zero come from? Why is it infinity?
Did you graph the function? (See below.)

-Dan

9. can someone explain this in words to me? so is it all positive real numbers?

10. Originally Posted by iheartthemusic29
can someone explain this in words to me? so is it all positive real numbers?
Almost. The range is all positive real numbers and 0.

Is it the notation $[0, \infty)$ that's bothering you?

-Dan

11. yes, but I think I understand it now.