Rationalize the Denominator

[zevenzeros]

I have tried everything even used 2 different websites and i cant get the answer. Any help would be appreciated. I have a feeling none of these answers are correct.

 

[tkhunny]

Utilize this principle: (a+b)(a-b) = a^2 - b^2

Okay, so the denominator will be c - d. You can rule out one choice immedaitely.

 

[Harry_the_cat]

Multiply top and bottom by \(\displaystyle \sqrt{c}+\sqrt{d}\)

 

[Steven G]

You could always pick values for a, b, c and d. I would choose a=b=d=1 and c=4. Evaluate the given expression and then evaluate all the choices. Only one will work!

However you should be able to rationalize the denominator!

Please do so and show us your work.

 

[zevenzeros]

Thanks the suggestions helped, figured out the answer is A.