Question : If ${P}+\frac{1}{{P}}=5$, then what is the value of ${P}^3+\frac{1}{{P}^3}$?
Option 1: 110
Option 2: 95
Option 3: 125
Option 4: 120
Recommended: How to crack SSC CHSL | SSC CHSL exam guide
Don't Miss: Month-wise Current Affairs | Upcoming government exams
Correct Answer: 110
Solution :
${P}+\frac{1}{{P}}=5$
Cubing both sides, we get,
$(a+b)^3 = a^3 + b^3 + 3ab(a+b)$
⇒ $({P}+\frac{1}{{P}})^3=5^3$
⇒ $P^3 + \frac{1}{P^3} + 3(P+\frac{1}{P})=125$
⇒ $P^3 + \frac{1}{P^3} + 3(5)= 125$
⇒ $P^3+\frac{1}{P^3}= 125-15$
⇒ $P^3 + \frac{1}{P^3} = 110$
Hence, the correct answer is 110.
Related Questions
Know More about
Staff Selection Commission Combined High ...
Answer Key | Eligibility | Application | Admit Card | Preparation Tips | Result | Cutoff
Get Updates Brochure
Your Staff Selection Commission Combined Higher Secondary Level Exam brochure has been successfully mailed to your registered email id “”.
