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: $9 \frac{3}{4}$
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Correct Answer: $7 \frac{1}{4}$
Solution : $2x^2 – 7x + 5 = 0$ $⇒2x^2 + 5 = 7x$ Dividing by $2x$, we get, $⇒x + \frac{5}{2x} = \frac{7}{2}$ Squaring both sides, we get, $⇒(x + \frac{5}{2x})^2 = (\frac{7}{2})^2$ $⇒x^2 + (\frac{5}{2x})^2 + 2 × x × \frac{5}{2x} = \frac{49}{4}$ $⇒x^2 + \frac{25}{4x^2} + 5 = \frac{49}{4 }$ $⇒x^2 + \frac{25}{4x^2} = \frac{49}{4} - 5$ $⇒x^2 + \frac{25}{4x^2} = \frac{29}{4}$ $\therefore x^2 + \frac{25}{4x^2} = 7\frac{1}{4}$ Hence, the correct answer is $7\frac{1}{4}$.
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Question : If $x^2-\sqrt{7} x+1=0$, then what is the value of $x^5+\frac{1}{x^5} ?$
Option 1: $19 \sqrt{7}$
Option 2: $21 \sqrt{7}$
Option 3: $25 \sqrt{7}$
Option 4: $27 \sqrt{7}$
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 : If $x^{2} -3x +1=0$, then the value of $\frac{\left(x^4+\frac{1}{x^2}\right)}{\left(x^2+5 x+1\right)}$ is:
Option 1: $\frac{9}{4}$
Option 2: $\frac{27}{8}$
Option 3: $\frac{5}{2}$
Option 4: $2$
Question : If $x+\left [\frac{1}{(x+7)}\right]=0$, what is the value of $x-\left [\frac{1}{(x+7)}\right]$?
Option 1: $3\sqrt{5}$
Option 2: $3\sqrt{5}-7$
Option 3: $3\sqrt{5}+7$
Option 4: $8$
Question : If $x-\frac{1}{x}=5, x \neq 0$, then what is the value of $\frac{x^6+3 x^3-1}{x^6-8 x^3-1} ?$
Option 1: $\frac{3}{8}$
Option 2: $\frac{13}{12}$
Option 3: $\frac{4}{9}$
Option 4: $\frac{11}{13}$
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