Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If x4 + \(\frac{1}{x^4}\) = 82367, the positive value of x + \(\frac{1}{x}\) is?

Options:

17

19

13

15

Correct Answer:

17

Explanation:

If x4 + \(\frac{1}{x^4}\) = a

then x2 + \(\frac{1}{x^2}\) = \(\sqrt {a + 2}\) = b

and x + \(\frac{1}{x}\) = \(\sqrt {b + 2}\)

ATQ,

x4 + \(\frac{1}{x^4}\) = 82367

x2 + \(\frac{1}{x^2}\) = \(\sqrt {82367 + 2}\) = 287

So, x + \(\frac{1}{x}\) = \(\sqrt {287 + 2}\) = 17