This could be just a tip ... couldn't you simplify the logs as a first step?
8logn = logx^2/3 + log2 - 1/2logx + logx^3 - log2/x^4[/quote]
8logn = logx2/3 + log2 - 1/2logx + logx3 - log2/x4
logn8 =log(x2/3 *2)-log(x1/2 *x3)-log2/x4
logn8=log2x2/3-logx7/2-log2/x4
logn8= log (2x2/3/ x7/2)- log2/x4
logn8= log2x-17/6- log2/x4
logn8= log (2x-17/6/2/x4)
logn8= log (x7/4)
n8=x9/4
n=(x7/4)1/8