If x + \(\frac{1}{x}\) = 9 then fi

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Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x + \(\frac{1}{x}\) = 9

then find the value of x - \(\frac{1}{x}\).

Options:

\(\sqrt {73 }\)

\(\sqrt {85 }\)

\(\sqrt {79 }\)

\(\sqrt {77 }\)

Correct Answer:

\(\sqrt {77 }\)

Explanation:

⇒ If x + \(\frac{1}{x}\) = a then x - \(\frac{1}{x}\) = \(\sqrt {a^2 - 4}\)

Here,

x + \(\frac{1}{x}\) = 9, then

⇒ x - \(\frac{1}{x}\) = \(\sqrt {9^2 - 4}\) = \(\sqrt {77 }\)