Consider the function f(x) = x^4 - 4x^2

(a) What are the roots (zeros) of f? (This simply means the solutions to the equation f(x) = 0 - no calculus needed.)

(b) On what interval(s) is f increasing? On what interval(s) is f decreasing?

(c) On what interval(s) is f concave up? On what interval(s) is f concave down?

(d) Sketch a graph of f, labeling the points you found above