ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: 9_7 on May 23, 2012, 06:15:54 pm

Title: Linear Programming help!! :(
Post by: 9_7 on May 23, 2012, 06:15:54 pm

Hey guys, i need help with where to shade the region wanted from your graph, how do you determine where to shade?! cheers

Title: Re: Linear Programming help!! :(
Post by: Stick on May 23, 2012, 08:50:08 pm

You need to test a point (the origin tends to be a good choice). If the inequality still holds truth after substituting a particular point, it means that point lies within the required region. :)

Title: Re: Linear Programming help!! :(
Post by: paulsterio on May 23, 2012, 08:53:30 pm

if y > f(x), region required is ABOVE the graph

if y < f(x), region required is BELOW the graph

Title: Re: Linear Programming help!! :(
Post by: djsandals on June 01, 2012, 10:08:45 pm

Quote from: Stick on May 23, 2012, 08:50:08 pm

You need to test a point (the origin tends to be a good choice). If the inequality still holds truth after substituting a particular point, it means that point lies within the required region. :)

Just make sure you don't test the origin if the line passes through it :)

Title: Re: Linear Programming help!! :(
Post by: djsandals on June 02, 2012, 05:31:17 pm

Quote from: paulsterio on May 23, 2012, 08:53:30 pm

if y > f(x), region required is ABOVE the graph

if y < f(x), region required is BELOW the graph

Only thing about this method is that the inequality must be in y=mx+c form.

Title: Re: Linear Programming help!! :(
Post by: MissJannine on June 04, 2012, 07:06:16 pm

Yeah a common test point is (0,0)

So for example if the constraint is y<2x+3 you substitute (0,0) into the equation so you will end up with 0<3. 0 is less than 3 so the constraint is true. Shade away from the point (0,0) Repeat with all constraints and the area that remains unshaded is the feasible region.