Question : If $x^{3}-y^{3}=81$ and $x-y=3$, what is the value of $x^{2}+y^{2}$?
Option 1: 18
Option 2: 21
Option 3: 27
Option 4: 36
Latest: SSC CGL Tier 1 Result 2024 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: 21
Solution : Given: $x^{3}-y^{3}=81$ and $x-y=3$ We know, $x^{3}-y^{3}=(x-y)^{3}+3xy(x-y)$ Substituting the values of $x^{3}-y^{3}$ and $x-y$, we get, $81=3^{3}+3×3xy$ $⇒xy=6$ Now, $x^{2}+y^{2}=(x-y)^{2}+2xy=3^{2}+2\times 6=21$ Hence, the correct answer is 21.
Candidates can download this ebook to know all about SSC CGL.
Result | Eligibility | Application | Selection Process | Preparation Tips | Admit Card | Answer Key
Question : If $x^2-xy+y^2=2$ and $x^4+x^2y^2+y^4=6$, then the value of $(x^2+xy+y^2)$ is:
Question : If $x=\sqrt[3]{28}, y=\sqrt[3]{27}$, then the value of $x+y-\frac{1}{x^{2}+xy+y^{2}}$ is:
Question : If $(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}) = 0$ and $x+y+z = 9$, what is the value of $x^{3} + y^{3}+z^{3}-xyz$?
Question : What is the value of $64 x^3+38 x^2 y+20 x y^2+y^3$, when $x=3$ and $y=-4$?
Question : If x + y = 36, then find (x – 27)3 + (y – 9)3.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile