# Finding the domain....urgent help needed

• Dec 13th 2007, 02:52 PM
aikenfan
Finding the domain....urgent help needed
How do I find the domain? Could someone please assist me through one of these problems? I vaguely remember going over this but I need to review this material...any assistance would be great!
http://i103.photobucket.com/albums/m...ntitled111.jpg
• Dec 13th 2007, 02:55 PM
Krizalid
$f(x)=\sqrt{x+2}.$

$x+2\ge0,$ 'cause you cannot have a negative quantity.

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For the second one, observe that $x^2+3x-10=(x-2)(x+5).$ What should it be the expected domain?
• Dec 13th 2007, 02:56 PM
aikenfan
would it be X + 5? because you cannot have a negative?
• Dec 13th 2007, 02:59 PM
Krizalid
Not exactly.

On the denominator, the values $2,-5$ make this one zero, then you'll get something like $\frac a0$ and that deserves a punishment.

So the domain will be $\text{Dom}\,f=\mathbb R-\{2,-5\}.$