Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x2 = (\(\sqrt {2}\) -1)\(\frac{1}{2}\), then find the value of x2 + \(\frac{1}{x^2}\).

Options:

2

2\(\sqrt {2}\)

0

1

Correct Answer:

2\(\sqrt {2}\)

Explanation:

x2 = \(\frac{1}{\sqrt {2} - 1}\) × \(\frac{\sqrt {2} + 1}{\sqrt {2} + 1}\) = \(\sqrt {2}\) + 1

\(\frac{1}{x^2}\) = \(\sqrt {2}\) - 1

x2 + \(\frac{1}{x^2}\) = \(\sqrt {2}\) + 1 + \(\sqrt {2}\) - 1

= 2\(\sqrt {2}\)