# Finding x intercepts of a function.

• Oct 8th 2012, 11:45 AM
alane1994
Finding x intercepts of a function.
y=x√x+9
I am supposed to have the answer as an ordered pair, give an "exact" answer using radicals as needed... Any thoughts? I got (0,0), but I am wrong...
• Oct 8th 2012, 11:51 AM
TheEmptySet
Re: Finding x intercepts of a function.
Quote:

Originally Posted by alane1994
y=x√x+9
I am supposed to have the answer as an ordered pair, give an "exact" answer using radicals as needed... Any thoughts? I got (0,0), but I am wrong...

To find the x intercepts you set y=0. This gives

$\displaystyle 0=x\sqrt{x}+9 \iff -9=x^{\frac{3}{2}}$

If x has to be a real number this equation has no solutions.
• Oct 8th 2012, 11:58 AM
alane1994
Re: Finding x intercepts of a function.
I should have been more specific... it is $\displaystyle x\sqrt{x+9}$I am doing this on an online program for my calculus course... I just ran out of attempts on this problem and it changed the problem...
$\displaystyle x\sqrt{x+6}$
• Oct 8th 2012, 04:56 PM
hollywood
Re: Finding x intercepts of a function.
For $\displaystyle x\sqrt{x+6}$ to be zero, you can have either $\displaystyle x=0$ or $\displaystyle \sqrt{x+6}=0$. So there are two x intercepts.

Online homework systems can be picky about the format of the answer. Some systems let you do a practice problem where you can view the answer - then you will know the format of the answer.

- Hollywood