Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $(2x + \frac{1}{2x}) = 5$, then what is the value of $(8x^3 + \frac{1}{8x^3})$ ?

Options:

110

120

100

125

Correct Answer:

110

Explanation:

If x + \(\frac{1}{x}\)  = n

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

If $(2x + \frac{1}{2x}) = 5$

then, $(8x^3 + \frac{1}{8x^3})$ = 53 - 3 × 5 = 110