Hey everybody, I just had a quick question about domain and how to write them in interval notation (I think that's what it's called).

So I have one problem,

$\displaystyle

f(x)=\frac {2x-5}{x^2-5x-6}

$

For this problem I got the domain:

$\displaystyle

(-\infty, -1) \cup (-1, 6) \cup (6, \infty)

$

For the other problem,

$\displaystyle

f(x)= \frac {2x-7}{x^2-x-12}

$

with this domain:

$\displaystyle

(-\infty, -3) \cup (4, \infty)

$

My question is this: why are there two 'U' in the first domain but not the second one? Have I just written the second one incorrectly? Any help is appreciated!