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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Correct Answer: $\frac{182}{125}$
Solution : Given, $5 x^2+7 x+5=0$ ⇒ $5x^2+5 = -7x$ Dividing both sides by $5x$, we get, ⇒ $x+\frac{1}{x}=-\frac{7}{5}$ -----------------(1) Cubing both sides, we get, ⇒ $x^3+\frac{1}{x^3}+3(x+\frac{1}{x})=-\frac{343}{125}$ ⇒ $x^3+\frac{1}{x^3}+3(-\frac{7}{5})=-\frac{343}{125}$ ⇒ $x^3+\frac{1}{x^3}=-\frac{343}{125}+\frac{21}{5}$ $\therefore x^3+\frac{1}{x^3}=\frac{182}{125}$ Hence, the correct answer is $\frac{182}{125}$.
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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 : 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 $x=2+\sqrt3$, then the value of $\frac{x^{2}-x+1}{x^{2}+x+1}$ is:
Option 1: $\frac{2}{3}$
Option 2: $\frac{3}{4}$
Option 3: $\frac{4}{5}$
Option 4: $\frac{3}{5}$
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 $\frac{10x}{3}+\frac{5}{2}(2-\frac{x}{3})=\frac{7}{2}$, then the value of $x$ is:
Option 1: $\frac{3}{5}$
Option 2: $-\frac{5}{3}$
Option 3: $\frac{5}{3}$
Option 4: $-\frac{3}{5}$
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