Function y=2x? The derivative function of-x 4 is:

y'= -4x？ + 6x？ = 2x？ (-2x+3)

When x≤3/2 and y'≥0, y is increasing function.

When x > 3/2 and y'< 0, y is a decreasing function.

To sum up:

The monotonic increasing interval of the function y is (-∞, 3/2),

The monotone decreasing interval is (3/2, +∞).

The extreme value is y=2×(3/2)? - (3/2)^4 = 27/ 16

The extreme point is (3/2,27/16).