# Homework Help: Finding domain

1. Nov 6, 2007

### Ry122

Can someone please tell me why the domain of y=2x^2+12x+12 is x elementof IR

2. Nov 6, 2007

### mjsd

because the function (of x) is defined for all x in R. It takes any value x in R as a valid input to the function.

3. Nov 6, 2007

### Ry122

What does IR mean exactly?

4. Nov 6, 2007

### mjsd

I don't know... you tell me? ... judging by the look of it, it looks like
$$\mathbb{R}$$
which means the real line.