(a) 198
\(a^4 + \frac{1}{a^4}\) = 1154 ⇒ \(a^4 + 2 + \frac{1}{a^4}\) = 1154 + 2
⇒ \(\bigg(a^2+\frac{1}{a^2}\bigg)^2\) = 1156 ⇒ \(a^2 + \frac{1}{a^2} = 34\)
⇒ \(a^2 + 2 + \frac{1}{a^2}\) = 34 + 2 ⇒ \(\bigg(a+\frac{1}{a}\bigg)^2\) = 36
\(a+\frac{1}{a}\) = 6