Minimizing and Maximizing Quadratic Expressions with Constraints

a) What is the minimum value of $32x^2 + \frac{1}{8x^2}$ for $x \neq 0$?
b) At which value of $x$ is this minimum achieved?
c) What is the maximum value of $32x + \frac{1}{8x}$ for negative values of $x$?
d) At which value of $x$ is this maximum achieved?