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If $$x + \frac{1}{x} = 5,$$ then what is the value of $${x^6} + \frac{1}{{{x^6}}}?$$
Answer & Solution
Correct Answer:
Option
C
$$\eqalign{
& x + \frac{1}{x} = 5 \cr
& {\text{Cubing both sides, we get}} \cr
& {x^3} + \frac{1}{{{x^3}}} + 3 \times x \times \frac{1}{x}\left( {x + \frac{1}{x}} \right) = 125 \cr
& {x^3} + \frac{1}{{{x^3}}} + 3 \times 5 = 125 \cr
& {x^3} + \frac{1}{{{x^3}}} = 110 \cr
& {\text{Squaring both sides, we get}} \cr
& {x^6} + \frac{1}{{{x^6}}} + 2 = 12100 \cr
& {x^6} + \frac{1}{{{x^6}}} = 12098 \cr} $$
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