(12 points) Given the function $f(x) = e^x(e^x - a) - a^2x$. (1) Discuss the monotonicity of $f(x)$; (2) If $f(x) \geq 0$, find the range of values for $a$.
(12 points)
Given the function $f(x) = e^x(e^x - a) - a^2x$.
(1) Discuss the monotonicity of $f(x)$;
(2) If $f(x) \geq 0$, find the range of values for $a$.