If $x^4 + (\frac{1}{x^4}) = 322,$ then what is the value of $x^3 - (\frac{1}{x^3})$ ?
Answer & explanation
Correct answer: option 2
If x4 + \(\frac{1}{x^4}\) = a
then x2 + \(\frac{1}{x^2}\) = \(\sqrt {a + 2}\) = b
and x - \(\frac{1}{x}\) = \(\sqrt {b - 2}\)
If $x^4 + (\frac{1}{x^4}) = 322,$
then x2 + \(\frac{1}{x^2}\) = \(\sqrt {322 + 2}\) = 18
and x - \(\frac{1}{x}\) = \(\sqrt {18 - 2}\) = 4
If x - \(\frac{1}{x}\) = n
then, $x^3 - \frac{1}{x^3}$ = 43 + 3 × 4 = 76