A) \[\frac{65}{8}\]
B) 8
C) \[7\frac{5}{8}\]
D) \[9\frac{3}{4}\]
Correct Answer: A
Solution :
[a] \[a+\frac{1}{a}=\frac{5}{2}\] \[\Rightarrow \,{{a}^{3}}+\frac{1}{{{a}^{3}}}={{\left( a+\frac{1}{a} \right)}^{3}}-3\left( a+\frac{1}{a} \right)\] \[=\frac{125}{8}-3\times \frac{5}{2}=\frac{65}{8}.\]You need to login to perform this action.
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