Question : If $x+\frac{1}{x}=7$, find the value of $x^3+\frac{1}{x^3}$.
Option 1: 343
Option 2: 322
Option 3: 340
Option 4: 332
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Correct Answer: 322
Solution : $x+\frac{1}{x}=7$ Squaring on both sides, ⇒ $(x+\frac{1}{x})^2=7^2$ ⇒ $x^2+\frac{1}{x^2}+2=49$ ⇒ $x^2+\frac{1}{x^2}=47$ Now, $x^3+\frac{1}{x^3} = (x+\frac{1}{x})(x^2+\frac{1}{x^2}-(x×\frac{1}{x}))$ = 7 × (47 – 1) = 322 Hence, the correct answer is 322.
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Question : If $x+\frac{1}{x}=6$, then find the value of $\frac{3 x}{2 x^2-5 x+2}$.
Option 1: $1$
Option 2: $\frac{3}{7}$
Option 3: $\frac{2}{3}$
Option 4: $0$
Question : In a right triangle for an acute angle $x$, if $\sin x=\frac{3}{7}$, then find the value of $\cos x$.
Option 1: $\frac{2}{7}$
Option 2: $\frac{3}{4}$
Option 3: $\frac{1}{\sqrt{3}}$
Option 4: $\frac{2\sqrt{10}}{7}$
Question : If $2 x^2-7 x+5=0$, then what is the value of $x^2+\frac{25}{4 x^2} ?$
Option 1: $5 \frac{1}{2}$
Option 2: $7 \frac{1}{4}$
Option 3: $9 \frac{1}{2}$
Option 4: $9 \frac{3}{4}$
Question : When $2x+\frac{2}{x}=3$, then the value of ($x^3+\frac{1}{x^3}+2)$ is:
Option 2: $\frac{7}{8}$
Option 3: $\frac{7}{2}$
Option 4: $\frac{8}{7}$
Question : If, for a non-zero $x, 5 x^2+7 x+5=0$, then the value of $x^3+\frac{1}{x^3}$ is:
Option 1: $\frac{496}{125}$
Option 2: $\frac{532}{343}$
Option 3: $\frac{125}{532}$
Option 4: $\frac{182}{125}$
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