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If x=2−3x=2-\sqrt3x=2−3​​, then x−1xx - \frac{1}{x}x−x1​​ is:
Question

If x=23x=2-\sqrt3​, then x1xx - \frac{1}{x}​ is:

A.

1230312-30\sqrt3​​

B.

535\sqrt3​​

C.

23-2\sqrt3​​

D.

333\sqrt3​​

Correct option is C

Given:

x=23x = 2 - \sqrt{3}​​​

We need to find the value of x1x.x - \frac{1}{x}.​​

Solution:

1x=123×2+32+3=2+3(23)(2+3)\frac{1}{x} = \frac{1}{2 - \sqrt{3}} \times \frac{2 + \sqrt{3}}{2 + \sqrt{3}} = \frac{2 + \sqrt{3}}{(2 - \sqrt{3})(2 + \sqrt{3})}=2+343\frac{2+\sqrt3}{4- 3}​​

Thus, we have:

1x=2+3\frac{1}{x} = 2 + \sqrt{3}​​

Now we can compute:

x1x=(23)(2+3)x - \frac{1}{x} = (2 - \sqrt{3}) - (2 + \sqrt{3})​​

x1x=2323=23x - \frac{1}{x} = 2 - \sqrt{3} - 2 - \sqrt{3} = -2\sqrt{3}

Option (C) is right.

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