Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x = 2 + \(\sqrt {3}\)

Find \(\frac{x^2 - x + 1}{x^2 + 1 + x}\)

Options:

\(\frac{2}{3}\)

\(\frac{3}{4}\)

\(\frac{4}{5}\)

\(\frac{3}{5}\)

Correct Answer:

\(\frac{3}{5}\)

Explanation:

Formula → If x = a + b and a2 - b2 = 1, then \(\frac{1}{x}\) = a - b always

⇒ x = 2 + \(\sqrt {3}\)

⇒ \(\frac{1}{x}\) = 2 - \(\sqrt {3}\)

Now put the values and find,

\(\frac{x + \frac{1}{x} - 1}{x + \frac{1}{x} + 1}\) = \(\frac{2 + \sqrt {3} + 2 - \sqrt {3} - 1}{2 + \sqrt {3} + 2 - \sqrt {3} + 1}\) = \(\frac{3}{5}\)