Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $x^4 + x^{-4} = 194, x > 0$, then what is the value of $X + \frac{1}{x} + 2$ ?

Options:

8

14

6

4

Correct Answer:

6

Explanation:

If x4 + \(\frac{1}{x^4}\) = a

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

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

If $x^4 + x^{-4} = 194

then x2 + \(\frac{1}{x^2}\) = \(\sqrt {194 + 2}\) = 14

and x + \(\frac{1}{x}\) = \(\sqrt {14 + 2}\) = 4

$X + \frac{1}{x} + 2$ = 4 + 2 = 6