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If $$x + \frac{1}{x} = 5{\text{,}}$$ then the value of $$\frac{{{x^4} + 3{x^3} + 5{x^2} + 3x + 1}}{{{x^4} + 1}} = ?$$
Answer & Solution
Correct Answer:
Option
A
$$\eqalign{
& x + \frac{1}{x} = 5 \cr
& \left( {{\text{By squaring both sides}}} \right) \cr
& {x^2} + \frac{1}{{{x^2}}} + 2.x.\frac{1}{x} = {\left( 5 \right)^2} \cr
& {x^2} + \frac{1}{{{x^2}}} = 23 \cr
& {\text{Now,}} \cr
& \frac{{{x^4} + 3{x^3} + 5{x^2} + 3x + 1}}{{{x^4} + 1}} \cr
& {\text{Divided by }}{x^2}, \cr
& \Rightarrow \frac{{\frac{{{x^4}}}{{{x^2}}} + \frac{{3{x^3}}}{{{x^2}}} + \frac{{5{x^2}}}{{{x^2}}} + \frac{{3x}}{{{x^2}}} + \frac{1}{{{x^2}}}}}{{\frac{{{x^4}}}{{{x^2}}} + \frac{1}{{{x^2}}}}} \cr
& \Rightarrow \frac{{{x^2} + 3x + 5 + \frac{3}{x} + \frac{1}{{{x^2}}}}}{{{x^2} + \frac{1}{{{x^2}}}}} \cr
& \Rightarrow \frac{{{x^2} + \frac{1}{{{x^2}}} + 3\left( {x + \frac{1}{x}} \right) + 5}}{{{x^2} + \frac{1}{{{x^2}}}}} \cr
& \Rightarrow \frac{{23 + 3\left( 5 \right) + 5}}{{23}} \cr
& \Rightarrow \frac{{43}}{{23}} \cr} $$
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