Find the x-coordinates of all critical points of the given function. Determine whether each critical point is a relative maximum, minimum, or neither by first applying the second derivative test, and, if the test fails, by some other method.

f(x) = 3x⁴ 2x³

f has ---Select--- a relative maximum a relative minimum no relative extrema at the critical point x =

. (smaller x-value)

f has ---Select--- a relative maximum a relative minimum no relative extrema at the critical point x =

. (larger x-value)