Help me with some calculus questions which I couldn't go through...

a) Find the intervals on which function is increasing and decreasing ?

f(x) = x^3 - 3x^2

b) Find the intervals on which function is increasing and decreasing ?

f(x) = 1 / x^2

c) what are critical numbers for:

i) f(x) = x^3 - 3x^2 and

ii) f(x) = 3x^4 - 4x^3

d) For which interval the function f(x) = 8x^3 - 2x^4 is concave downwards?

e) Find the points of inflection for f(x) = x^4 - x^3 ...