(a) In the expansion of \(\left(x+x^{2}\right)^{8}\) in ascending powers of \(x\), the 3rd and 6th terms are equal. Find the value of \(x\).

(b) In the expansion of \(\left(x+\frac{2}{x}\right)^{n}\) in decreasing powers of \(x\), the 6th term is a constant. (i) Find the value of the positive integer \(n\).

(ii) Find the value of the 6th term.