Question 133

If $$(3x^{2}-9x+3)=0$$, then what is the value of $$(x+\frac{1}{x})^{3}$$ ?

Solution

Given : $$(3x^{2}-9x+3)=0$$

=> $$(3x^{2}+3)=9x$$

Dividing both sides by $$'3x'$$, we get :

=> $$x+\frac{1}{x}=3$$ -------------(i)

Cubing both sides,

=> $$(x+\frac{1}{x})^3=(3)^3$$

=> $$(x+\frac{1}{x})^3=27$$

=> Ans - (D)

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