Rationalizing the denominator

[slickergal15]

I am seriously struggling and appreciate all the help I can get. This is what the problem looks on the worsheet. There are no bracket or anything.
Rationalize the denominator .assume that all expressions underradicals respresent positive numers. I first changed 16x into 4 and multiplied 7*4 but then I noticed not one of the given answers has 28 so I knew I was wrong from the start.

7?16y
-------
?x^3

the possible answers are:
a. 7y?16

b. 7?16y
-------
y

c. 7?16
-------
y

d. 112
------
y

 

[mmm4444bot]

7?16y ? This notation shows y outside of the radical
-------
?x^3

I first changed 16x into 4 From where did 16x come ?

Is the symbol y underneath the radical sign?

Please confirm that the numerator is 7 * sqrt(16) * y

and not 7 * sqrt(16y)

Either way, it seems that you'll end up with 28 in the numerator, but I'll wait until you confirm the actual expression appearing over sqrt(x^3).

Cheers ~ Mark

 

[slickergal15]

Hi Mark,
First let me say thank you for your time.

Next let me clarify how it is written:
the 16y is completely inside the top radical
then (denominator) y^3 not x^3 is also completely under radical

 

[mmm4444bot]

Okay, the given expression is clear to me now.

7 sqrt(16y)/sqrt(y^3)

The rationalized result is 28/y, so none of the multiple choices are correct.

By the way, there is a [Preview] button next to the [Submit] button. You can use it to proofread your posts, before submission; you might have caught your typographical errors (in the denominator and "16x").

Cheers!