2 Views

Question : If $x+\frac{1}{x}=3$, then the value of $x^5+\frac{1}{x^5}$ is:

Option 1: 322

Option 2: 126

Option 3: 123

Option 4: 113


Team Careers360 2nd Jan, 2024
Answer (1)
Team Careers360 13th Jan, 2024

Correct Answer: 123


Solution : Given: $x+\frac{1}{x}=3$
$x^2+\frac{1}{x^2}=(x+\frac{1}{x})^2-2=3^2-2=7$.
Similarly, $x^3+\frac{1}{x^3}=(x+\frac{1}{x})^3-3×x×\frac{1}{x}(x+\frac{1}{x})=3^3-3\times 3=18$.
Now, $x^5+\frac{1}{x^5}=(x^2+\frac{1}{x^2})(x^3+\frac{1}{x^3})-(x+\frac{1}{x})$
Putting the values of $x^2+\frac{1}{x^2}$ and $x^3+\frac{1}{x^3}$, we get:
$\therefore x^5+\frac{1}{x^5}=7\times 18-3=123$
Hence, the correct answer is 123.

How to crack SSC CHSL

Candidates can download this e-book to give a boost to thier preparation.

Download Now

Know More About

Related Questions

TOEFL ® Registrations 2024
Apply
Accepted by more than 11,000 universities in over 150 countries worldwide
Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
GRE ® Registrations 2024
Apply
Apply for GRE® Test now & save 10% with ApplyShop Gift Card | World's most used Admission Test for Graduate & Professional Schools
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books