If $a^4 +\frac{1}{a^4} = 194$, then what is the value of $\frac{a^6+1}{a^3}$ ?
Answer & explanation
Correct answer: option 3
If x4 + \(\frac{1}{x^4}\) = a
then x2 + \(\frac{1}{x^2}\) = \(\sqrt {a + 2}\) = b
and x + \(\frac{1}{x}\) = \(\sqrt {b + 2}\)
According to the question,
$a^4 +\frac{1}{a^4} = 194$
then a2 + \(\frac{1}{a^2}\) = \(\sqrt {194 + 2}\) = 14
and a + \(\frac{1}{a}\) = \(\sqrt {14 + 2}\) = 4
If x + \(\frac{1}{x}\) = n
then, $x^3 +\frac{1}{x^3}$ = n3 - 3 × n
$\frac{a^6+1}{a^3}$ = 43 - 3 × 4 = 52