Question : When $2x+\frac{2}{x}=3$, then the value of ($x^3+\frac{1}{x^3}+2)$ is:
Option 1: $\frac{2}{7}$
Option 2: $\frac{7}{8}$
Option 3: $\frac{7}{2}$
Option 4: $\frac{8}{7}$
Latest: SSC CGL preparation tips to crack the exam
Don't Miss: SSC CGL complete guide
New: Unlock 10% OFF on PTE Academic. Use Code: 'C360SPL10'
Correct Answer: $\frac{7}{8}$
Solution : Given: $2x+\frac{2}{x}=3$ ⇒ $x+\frac{1}{x}=\frac{3}{2}$ (Dividing both sides by 2) Now, $(x+\frac{1}{x})^3=(\frac{3}{2})^3$ (Taking cube on both sides) ⇒ $x^3+\frac{1}{x^3}+3×x×\frac{1}{x}(x+\frac{1}{x})=\frac{27}{8}$ ⇒ $x^3+\frac{1}{x^3}+3(\frac{3}{2})=\frac{27}{8}$ ⇒ $x^3+\frac{1}{x^3}=\frac{27}{8}–\frac{9}{2}$ ⇒ $x^3+\frac{1}{x^3}+2=\frac{27}{8}–\frac{9}{2}+2=\frac{27–36+16}{8}=\frac{7}{8}$ Hence, the correct answer is = $\frac{7}{8}$.
Candidates can download this ebook to know all about SSC CGL.
Answer Key | Eligibility | Application | Selection Process | Preparation Tips | Result | Admit Card
Question : If $2x+\frac{2}{x}=3$, then the value of $x^{3}+\frac{1}{x^{3}}+2$ is:
Question : If $2x-\frac{2}{x}=1(x \neq 0)$, then the the value of $(x^3-\frac{1}{x^3})$ is:
Question : If $2x+\frac{1}{2x}=2,$ what is the value of $\sqrt{2\left (\frac{1}{x}\right)^{4}+\left (\frac{1}{x}\right)^{5}}\; ?$
Question : If $2x-\frac{1}{2x}=5,x\neq0$, then the value of $(x^2+\frac{1}{16x^2}-2)$is:
Question : If $x=a+\frac{1}{a}$ and $y=a-\frac{1}{a}$, then the value of $x^4+y^4-2x^2y^2$ is:
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile