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Which choice is equivalent to the fraction below when [tex]$x$[/tex] is an appropriate value? Hint: Rationalize the denominator and simplify.

[tex] \frac{\sqrt{12}}{\sqrt{3}+3} [/tex]

A. [tex]-\sqrt{3}[/tex]

B. [tex]-1-\sqrt{3}[/tex]

C. [tex]-1-\sqrt{2}[/tex]

D. [tex]-1+\sqrt{3}[/tex]


Sagot :

Let's find which choice is equivalent to the given fraction by rationalizing the denominator and simplifying the expression.
Given:
[tex]\[ \frac{\sqrt{12}}{\sqrt{3} + 3} \][/tex]

The first step is to rationalize the denominator. To do this, we multiply both the numerator and the denominator by the conjugate of the denominator, which is [tex]\(\sqrt{3} - 3\)[/tex]:
[tex]\[ \frac{\sqrt{12}(\sqrt{3} - 3)}{(\sqrt{3} + 3)(\sqrt{3} - 3)} \][/tex]

Next, let's simplify the denominator:
[tex]\[ (\sqrt{3} + 3)(\sqrt{3} - 3) = (\sqrt{3})^2 - 3^2 = 3 - 9 = -6 \][/tex]

Now, we simplify the numerator:
[tex]\[ \sqrt{12} (\sqrt{3} - 3) = \sqrt{12} \cdot \sqrt{3} - \sqrt{12} \cdot 3 \][/tex]
Note that:
[tex]\[ \sqrt{12} = \sqrt{4 \cdot 3} = 2 \sqrt{3} \][/tex]
Therefore:
[tex]\[ \sqrt{12} \cdot \sqrt{3} = 2 \sqrt{3} \cdot \sqrt{3} = 2 \cdot 3 = 6 \][/tex]
and
[tex]\[ \sqrt{12} \cdot 3 = 2 \sqrt{3} \cdot 3 = 6 \sqrt{3} \][/tex]

So, the numerator becomes:
[tex]\[ 6 - 6\sqrt{3} \][/tex]

Putting it all together, we get:
[tex]\[ \frac{6 - 6\sqrt{3}}{-6} \][/tex]

We can simplify this expression further by dividing both terms in the numerator by -6:
[tex]\[ \frac{6}{-6} - \frac{6\sqrt{3}}{-6} = -1 + \sqrt{3} \][/tex]

Thus, the simplified expression is:
[tex]\[ -1 + \sqrt{3} \][/tex]

Therefore, the correct choice equivalent to the given fraction is:
[tex]\[ \boxed{-1+\sqrt{3}} \][/tex]

So, the answer is:
D. [tex]\(-1+\sqrt{3}\)[/tex]