Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $\sqrt{x} −\frac{1}{\sqrt{x}} = \sqrt{5}$, x ≠ 0, then what is the value of $\frac{(x^4+\frac{1}{x^2})}{(x^2+1)}$?

Options:

42

44

48

46

Correct Answer:

46

Explanation:

If $\sqrt{x} −\frac{1}{\sqrt{x}} = \sqrt{5}$

Then, $\sqrt{x} + \frac{1}{\sqrt{x}} = \sqrt{5^2 + 4}$ = 3

x + \(\frac{1}{x}\) = 32 - 2 = 7

If x + \(\frac{1}{x}\)  = n

then, $x^3 +\frac{1}{x^3}$ = n3 - 3 × n

$x^3 +\frac{1}{x^3}$ = 73 - 3 × 7 = 322

Now according to the question we have to find = $\frac{(x^4+\frac{1}{x^2})}{(x^2+1)}$

Take x common from numerator and denominator then we left with = $\frac{(x^3+\frac{1}{x^3})}{(x+\frac{1}{x})}$

= \(\frac{322}{7}\) = 46