Question : If $\left(x+\frac{1}{x}\right)=\sqrt{6}$ and $x>1$, what is the value of $\left(x^8-\frac{1}{x^8}\right)$?
Option 1: $120\sqrt{3}$
Option 2: $128\sqrt{3}$
Option 3: $112\sqrt{3}$
Option 4: $108\sqrt{3}$
Latest: SSC CGL 2024 final Result Out | SSC CGL preparation tips to crack the exam
Don't Miss: SSC CGL Tier 1 Scorecard 2024 Released | SSC CGL complete guide
Suggested: Month-wise Current Affairs | Upcoming Government Exams
Correct Answer: $112\sqrt{3}$
Solution : $\left(x+\frac{1}{x}\right)=\sqrt{6}$ Squaring both sides, $\left(x^2+\frac{1}{x^2}+2\right)=6$ ⇒ $x^4-4x^2+1=0$ ⇒ $x^2=\frac{4\pm2\sqrt{3}}2$ ⇒ $x^2 = 2+\sqrt{3}$ (Since $x>0$) Squaring both sides, ⇒ $x^4 = 7+4\sqrt{3}$ Squaring both sides ⇒ $x^8 = 97+56\sqrt{3}$ So, $\frac{1}{x^8}=97-56\sqrt{3}$ So, $x^8-\frac{1}{x^8}=112\sqrt{3}$ Hence, the correct answer is $112\sqrt{3}$.
Candidates can download this ebook to know all about SSC CGL.
Admit Card | Eligibility | Application | Selection Process | Preparation Tips | Result | Answer Key
Question : If $\left(x+\frac{1}{x}\right)=2 \sqrt{2}$ and $x>1$, what is the value of $\left(x^6-\frac{1}{x^6}\right)$?
Option 1: $140\sqrt{2}$
Option 2: $116\sqrt{2}$
Option 3: $144\sqrt{2}$
Option 4: $128\sqrt{2}$
Question : If $\left(x-\frac{1}{x}\right)^2=12$, what is the value of $\left(x^2-\frac{1}{x^2}\right)$, given that $x>0$?
Option 1: $6 \sqrt{2}$
Option 2: $8 \sqrt{3}$
Option 3: $6 \sqrt{3}$
Option 4: $8 \sqrt{2}$
Question : If $\left(x^2 - \frac{1}{x^2}\right) = 4 \sqrt{6}$ and $x>1$, what is the value of $\left(x^3 - \frac{1}{x^3}\right)?$
Option 1: $20 \sqrt{2}$
Option 2: $24 \sqrt{2}$
Option 3: $18 \sqrt{2}$
Option 4: $22 \sqrt{2}$
Question : If ${\left(x-\frac{1}{x}\right)=\sqrt{6}}$ and $x > 1$, what is the value of ${\left(x^8-\frac{1}{x^8}\right)}$?
Option 1: $1024 \sqrt{15}$
Option 2: $992 \sqrt{15}$
Option 3: $998 \sqrt{15}$
Option 4: $1012 \sqrt{15}$
Question : If $\left(x+\frac{1}{x}\right)=5$, and $x>1$, what is the value of $\left(x^8-\frac{1}{x^8}\right)?$
Option 1: $60605 \sqrt{21}$
Option 2: $60615 \sqrt{21}$
Option 3: $60705 \sqrt{21}$
Option 4: $60725 \sqrt{21}$
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile