Use the "guess" method to solve for x in the following equations. \begin{aligned} &\text { a) }\\ &x^{2}+6 x^{7}-\frac{6-x^{5 / 9}}{\left(x^{2}-1\right)}=47.6 \end{aligned} \begin{aligned} &\text { b) }\\ &\frac{\left(x^{2}+x^{5}\right)}{x^{3}}-1=x \end{aligned}