# plot feasible region of inequality function

• November 28th 2011, 12:32 PM
kare
plot feasible region of inequality function
hello all,
I need to know the method of plotting the feasible region of inequality function like the following nonlinear function
$(1-x1)^3-x2 >=0$

I know how to plot the region for the linear function like
$x1+x2<=5$ - line connect $x1=5$ to $x2=5$ with the region under the line as a feasible region.

Regards.
• November 28th 2011, 02:50 PM
TKHunny
Re: plot feasible region of inequality function
Why would a different sort of boundary pose any different process for plotting? Just find teh border and decide which side.

x2 <= (1-x1)^3

Okay, have you ever seen the function y = x^3? It should look a lot like that, only shifted one (1) to the right and reflected across the x-axis (flipped vertically). Can you see why there are TWO variations from y = x^3?

Your last task is to decide which side to shade. You can either wring your hands and wonder or you can just TRY something. (0,0) is a nice place to start unless it is on the boundary. Is this true: 0 <= (1-0)^3. If so, shade that side.
• November 28th 2011, 03:13 PM
kare
Re: plot feasible region of inequality function
Thank you TKHunny.
I understand now :).