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If $$x + \frac{1}{x} = 3{\text{,}}$$ then the value of $$\frac{{{x^3} + \frac{1}{x}}}{{{x^2} - x + 1}}\,{\text{is?}}$$
Answer & Solution
Correct Answer:
Option
C
$$\eqalign{
& x + \frac{1}{x} = 3{\text{ }}\left( {{\text{Given}}} \right) \cr
& \frac{{{x^3} + \frac{1}{x}}}{{{x^2} - x + 1}}{\text{ }}\left( {{\text{Divide by }}x} \right) \cr
& \Rightarrow \frac{{\frac{{{x^3}}}{x} + \frac{1}{{{x^2}}}}}{{\frac{{{x^2}}}{x} - \frac{x}{x} + \frac{1}{x}}} \cr
& \Rightarrow \frac{{{x^2} + \frac{1}{{{x^2}}}}}{{x - 1 + \frac{1}{x}}} \cr
& \Rightarrow \frac{{{x^2} + \frac{1}{{{x^2}}}}}{{x + \frac{1}{x} - 1}} \cr
& \therefore x + \frac{1}{x} = 3 \cr
& \therefore {x^2} + \frac{1}{{{x^2}}} = 9 - 2 = 7 \cr
& \therefore \frac{{{x^2} + \frac{1}{{{x^2}}}}}{{x + \frac{1}{x} - 1}} = \frac{7}{{3 - 1}} = \frac{7}{2} \cr} $$
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