Topic: beginner ..

Hello my name is Savvas and i admit that ''graph" is a very usefull & handy proggram(if you can use it of course).
However , as a beginner i cannot understand some, i suppose, easy things. For example i would like to insert a new function like 16x+20y.
Can anyone help me about this? It's the first step for me.

2 Reply by joe (edited by joe 2010-11-10 15:36:52)

  • joe
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Re: beginner ..

I suppose you want to write this:

16x+20y=0

Please correct me if I'm wrong.
If that is what you want there are basicly to ways to do this:

The one is to insert a relation (hotkey: "F6"), and here you can simply write it as: 16x+20y=0

The other is to insert a function (hotkey: "insert") where you've isolated "y", and it will look like this 16x/-20=y
Because:

16x+20y=0    -->    16x=-20y    -->    16/-20=y

In both cases x and y will "obey" the same rules and therefore the same graph will be displayed(:

Re: beginner ..

Well in fact i want to make a graph with this:

Objective function MINz = 16X+20Y

Constraints :

10X + 12Y ≤ 1.200
3X + 5Y ≥ 315
6X + 7Y ≥ 504
Χ, Y ≥ 0

Re: beginner ..

What is MINz?
Is it a 3D function?

Re: beginner ..

No i am sorry again...(beginner)

MIN means minimize the function Minimize  z= 16x+20y

Constraints :
10X + 12Y ≤ 1.200
3X + 5Y ≥ 315
6X + 7Y ≥ 504
Χ, Y ≥ 0

Re: beginner ..

I still don't understand what it is you want. z= 16x+20y has 3 variables, which means 3 axes. 3 axes are also called 3D. However Graph can only plot 2D functions.

Re: beginner ..

Maybe this added file can help you?

Post's attachments

Attachment icon Min.grf 937 b, 760 downloads since 2010-11-13 

Re: beginner ..

Ivan Johansen wrote:

I still don't understand what it is you want. z= 16x+20y has 3 variables, which means 3 axes. 3 axes are also called 3D. However Graph can only plot 2D functions.

Maybe, he want to graph the constrains only. not the z= 16x+20y. IMO.