# Math Help - Can someone help me with this question

1. ## Can someone help me with this question

Determine which expression is the correct rationalization of the denominator of

I would assume it is -5 but the answer is suppose to be B

The Question Is Here ^^

2. ## Re: Can someone help me witht his question

Just multiply numerator and denominator by $\sqrt{5} + \sqrt{10}$.

3. ## Re: Can someone help me with this question

hint ...

$\sqrt{5} \pm \sqrt{10} = \sqrt{5}(1 \pm \sqrt{2})$

4. ## Re: Can someone help me with this question

Originally Posted by waleedrabbani
Determine which expression is the correct rationalization of the denominator of

I would assume it is -5 but the answer is suppose to be B

The Question Is Here ^^
The denominator becomes -5, but you are not asked what does the denominator become. You are asked to give an expression that is EQUIVALENT to the expression which has been given, which has a rational denominator (and of course is fully simplified).

5. ## Re: Can someone help me with this question

I agree it is a weird question but I don't see how adding information would make it any less weird!

6. ## Re: Can someone help me with this question

Originally Posted by HallsofIvy
I agree it is a weird question but I don't see how adding information would make it any less weird!
I don't see what's so weird about it. The question asks the reader to write \displaystyle \begin{align*} \frac{\sqrt{5} + \sqrt{10}}{\sqrt{5} - \sqrt{10}} \end{align*} with a rational denominator. The OP has misinterpreted the question as asking what would the denominator becomes in the process of rationalising.