IDNLearn.com makes it easy to find precise answers to your specific questions. Find accurate and detailed answers to your questions from our experienced and dedicated community members.

Which choice is equivalent to the fraction below when [tex][tex]$x \geq 2$[/tex][/tex]?

Rationalize the denominator and simplify:

[tex]\frac{4}{\sqrt{x-2}-\sqrt{x}}[/tex]

A. [tex]-2(\sqrt{x}-\sqrt{x-2})[/tex]

B. [tex]2(\sqrt{x}+\sqrt{x-2})[/tex]

C. [tex]-2(\sqrt{x}+\sqrt{x-2})[/tex]

D. [tex]2(\sqrt{x}-\sqrt{x-2})[/tex]


Sagot :

Let's solve the problem step-by-step.

We start with the given fraction:
[tex]\[ \frac{4}{\sqrt{x-2} - \sqrt{x}} \][/tex]

To simplify this fraction, we rationalize the denominator by multiplying the numerator and the denominator by the conjugate of the denominator. The conjugate of [tex]\(\sqrt{x-2} - \sqrt{x}\)[/tex] is [tex]\(\sqrt{x-2} + \sqrt{x}\)[/tex].

Thus, we proceed as follows:
[tex]\[ \frac{4}{\sqrt{x-2} - \sqrt{x}} \times \frac{\sqrt{x-2} + \sqrt{x}}{\sqrt{x-2} + \sqrt{x}} = \frac{4 (\sqrt{x-2} + \sqrt{x})}{(\sqrt{x-2} - \sqrt{x})(\sqrt{x-2} + \sqrt{x})} \][/tex]

Next, we simplify the denominator using the difference of squares:
[tex]\[ (\sqrt{x-2} - \sqrt{x})(\sqrt{x-2} + \sqrt{x}) = (\sqrt{x-2})^2 - (\sqrt{x})^2 = (x-2) - x = -2 \][/tex]

So, the fraction becomes:
[tex]\[ \frac{4 (\sqrt{x-2} + \sqrt{x})}{-2} \][/tex]

This simplifies by dividing both the numerator and the denominator by [tex]\(-2\)[/tex]:
[tex]\[ \frac{4 (\sqrt{x-2} + \sqrt{x})}{-2} = -2 (\sqrt{x-2} + \sqrt{x}) \][/tex]

Now we compare this result with the given choices:

A. [tex]\(-2 (\sqrt{x} - \sqrt{x-2})\)[/tex]

B. [tex]\(2 (\sqrt{x} + \sqrt{x-2})\)[/tex]

C. [tex]\(-2 (\sqrt{x} + \sqrt{x-2})\)[/tex]

D. [tex]\(2 (\sqrt{x} - \sqrt{x-2})\)[/tex]

From our simplification, we have [tex]\(-2 (\sqrt{x-2} + \sqrt{x})\)[/tex], which matches choice C.

Therefore, the correct answer is:
[tex]\[ \boxed{C} \][/tex]