Question : If $k$ is the largest possible real number such that $p^{4}+q^{4}=(p^{2}+kpq+q^{2})(p^{2}-kpq+q^{2})$, then the value of $k$ is:
Option 1: $1$
Option 2: $–\sqrt{2}$
Option 3: $2$
Option 4: $\sqrt{2}$
New: SSC CGL 2025 Tier-1 Result
Latest: SSC CGL complete guide
Suggested: Month-wise Current Affairs | Upcoming Government Exams
Correct Answer: $\sqrt{2}$
Solution :
Given: $p^{4}+q^{4}=(p^{2}+kpq+q^{2})(p^{2}-kpq+q^{2})$ -----(1)
$p^{4}+q^{4}$
$=(p^{2})^{2}+(q^{2})^{2}$
$=(p^{2}+q^{2})^{2}-2p^{2}q^{2}$
$=(p^{2}+q^{2})^{2}-(\sqrt{2}pq)^{2}$
$=(p^{2}+\sqrt{2}pq+q^{2})(p^{2}-\sqrt{2}pq+q^{2})$
By comparing this with equation (1), we get,
$k=\sqrt{2}$
Hence, the correct answer is $\sqrt{2}$.
Related Questions
Know More about
Staff Selection Commission Combined Grad ...
Answer Key | Eligibility | Application | Selection Process | Preparation Tips | Result | Admit Card
Get Updates BrochureYour Staff Selection Commission Combined Graduate Level Exam brochure has been successfully mailed to your registered email id “”.




