A) 0
B) 1
C) 3
D) -3
Correct Answer: D
Solution :
(d): \[xy\left( x-y \right)=1\] \[\Rightarrow \left( y-x \right)=-\frac{1}{xy}\] Cubing, \[=-{{x}^{3}}+{{y}^{3}}-3xy(y-x)=\frac{-1}{{{x}^{3}}{{y}^{3}}}\] \[\Rightarrow \frac{1}{{{x}^{3}}{{y}^{3}}}-{{x}^{3}}+{{y}^{3}}=3xy(y-x)\] Since \[xy\left( x-y \right)=1\] \[\Rightarrow xy\left( y-x \right)=-1\] \[3xy\left( y-x \right)=-3\]You need to login to perform this action.
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