I faced a problem with the following syntax which provided me we partial circles inequality plotting, and how able to improve the syntax:
restart: with(plots):
inequal({y > -1, y >= x^2+1, (x-1)^2+(y-1)^2 <= 16}, x = -5 .. 8, y = -6 .. 6, optionsfeasible = (color = grey), optionsexcluded = (color = white));

I would like to plot a piecewise function. g := x -> piecewise(x < -1, x + 1, x = 1, 4, 2 < x, x^2) with showing the value of 4 using plot command. How to do that? 
As I using the command plot(g, -5 .. 5, -5 .. 5, discont = true, thickness = 3), the value of 4 when x = 1 did not show up.

I had another problem whereby I need to shaded a region between y=ln(x+2) , y-axis and y=-1 to y= 2. What is the suitable comand I shall apply ( Maple 18)

I would like to know , what is the command that i able to carry out (simple one) such that I able to shaded the region between y=x^2 and y-axis from y= 0 to y=4.

Piecewise function in Maple are continuous function. Now, how I able to write the commands for following discontinuous piecewise function?

and when find out f(0) the result is undefined?