If $$x^{4}+(\frac{1}{x^{4}})=34$$, then what is the value of $$x^{3}-(\frac{1}{x^{3}})$$ ?
Given : $$x^4+\frac{1}{x^4}=34$$
Adding 2 on both sides,
=> $$x^4+\frac{1}{x^4}+2(x^2)(\frac{1}{x^2})=34+2$$
=> $$(x^2+\frac{1}{x^2})^2=36$$
=> $$(x^2+\frac{1}{x^2})=\sqrt{36}=6$$
Now subtracting 2 from both sides, we get :
=> $$(x)^2+(\frac{1}{x})^2-2(x)(\frac{1}{x})=6-2$$
=> $$(x-\frac{1}{x})=2$$ ------------(i)
Cubing both sides, we get :
=> $$(x-\frac{1}{x})^3=(2)^3$$
=> $$x^3-\frac{1}{x^3}-3(x)(\frac{1}{x})(x-\frac{1}{x})=8$$
=> $$x^3-\frac{1}{x^3}-3(2)=8$$
=> $$x^3-\frac{1}{x^3}=8+6=14$$
=> Ans - (D)
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