Question
1.
2.
3.
4.
Answer (Detailed Solution Below)
Option 1 : $393$
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Detailed Solution
सही उत्तर $393$ है।
Key Points
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prepsnap.in • Part -AQuestion:
If $x - \frac{1}{x} = 3$, then the value of $x^{5} - \frac{1}{x^{5}}$ is / यदि $x - \frac{1}{x} = 3$ है, तो $x^{5} - \frac{1}{x^{5}}$ का मान है
1.
$393$
2.
$363$
3.
$420$
4.
$123$
Correct Answer: $393$
$x^{2}+\frac{1}{x^{2}} = 3^{2}+2 = 11$ and $x^{3}-\frac{1}{x^{3}} = 3^{3}+3\cdot3 = 36$. Then $x^{5}-\frac{1}{x^{5}} = (x^{3}-\frac{1}{x^{3}})(x^{2}+\frac{1}{x^{2}}) - (x-\frac{1}{x}) = 36\times11 - 3 = 393$. / मान $36\times11-3=393$। Option (b) is the trap of computing $3^{5}-3 = 240$ style shortcuts that mix up the signs.
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