# Homework Help: The domain of a function in interval notation

1. Mar 15, 2012

1. what is the domain of the function k(y)=1/(2y+1)? Express your answer in interval notation

2.

3. I find that 0.5 is a possibility in this function, but since i have not done functions at school, i do not really know much more of this question.

2. Mar 15, 2012

### e^(i Pi)+1=0

There are generally only two restrictions you have to look for when determining domain. If there is a fraction, the denominator cannot equal 0, and if there is an even numbered radical, the inside cannot be negative.

3. Mar 15, 2012

### HallsofIvy

"0.5 is a possibility" for what? It certainly is not the domain because it is not a interval. Are you claiming that 0.5 is in the domain?

4. Mar 19, 2012

So what really is meant by the domain? Is it asking for all possible values of y?

5. Mar 19, 2012

I mean that 0.5 could be y

6. Mar 19, 2012

### SammyS

Staff Emeritus
All possible values for x .

7. Mar 19, 2012

### HallsofIvy

Good question! You can't solve a problem about the "domain" if you don't know what that word means. Did you consider looking the word up in your textbook?

The "domain" of a function, f(x), is the set of all allowable values lf x. The set of all possible values of the function, y if we have y= f(x), is the "range" of the function.

8. Mar 19, 2012

### e^(i Pi)+1=0

the domain of f(x)=$\frac{2}{x-1}$ for example is all real numbers except 1, because when x is 1 the denominator goes to 0, and the equation becomes undefined.
This can be notated as D: x≠1 or D:(-∞,1)$\cup$(1,∞)