It is where the original function (its derivative) is positive and negative.

Thus, it decreases on

It increases on

It is where the derivative of this is increasing and decreasing. Quite difficult to tell from your picture.(2)where is F(x) concave up and concave down explain.

Where derivative is zero, at the max and min points of this graph.(3)where does F(x) has inflection point

Where derivative is zero, i.e. where it crosses the x-axis. Those are your critical points.(4) where F(x) has maxima and minima.