Solver could not find a feasible solution

[MrFuz]

Can someone help me using solver? solver says there is no feasible solution but I know there is. I’ve tried messing around with different solver methods and the options of solver but still can’t get it to work.

the two equations are:
x^2 * Y - 10^5 = 0
(3*Y) - (2*X) = 0

can someone try using solver to find values of X and Y? And send the file or a screensho?
(I have tried to upload an excel file or a picture but it doesn’t work.)

 

[StephenCrump]

Are you able to send a xl2bb screenshot or the excel file So I could see what you done. Or say step by step what to do on solver.

Here's your workbook (attached to post #7), with 10 changed to 10^12

	A	B	C	D	E	F
1
2			VALUES	UNKNOWNS	EQN	CONSTRAINT
3	X^2*Y-10^12=0		X		-1E+12	0
4	3Y-2X=0		Y		0	0
5
Sheet1

Cell Formulas
Range	Formula
E3	E3	=(D3^2)*D4-10^12
E4	E4	=(3*D4)-(2*D3)

Named Ranges
Name	Refers To	Cells
solver_adj	=Sheet1!$D$3:$D$4	E3:E4

If I try start values in x (cell D3) and y (D4) both equal to 10,000, like this ...

		VALUES	UNKNOWNS	EQN	CONSTRAINT
X^2*Y-10^12=0		X	10000	0	0
3Y-2X=0		Y	10000	10000	0

... and run your version of Solver, I get the solution:

Book5.xlsx
	A	B	C	D	E	F
1
2			VALUES	UNKNOWNS	EQN	CONSTRAINT
3	X^2*Y-10^12=0		X	11447.1424	0	0
4	3Y-2X=0		Y	7631.42828	0	0
5
Sheet1

Cell Formulas
Range	Formula
E3	E3	=(D3^2)*D4-10^12
E4	E4	=(3*D4)-(2*D3)

Named Ranges
Name	Refers To	Cells
solver_adj	=Sheet1!$D$3:$D$4	E3:E4

Similar happens if I start with guesses of x=y=10, but the "solution" lacks some precision.

 

[StephenCrump]

Solver says there is no feasible solution but I know there is.

Welcome to the Forum!

This sounds like a homework question, where you've been asked to find the solution? Hence you "know" there is a solution?

The two equations are easily solved using Solver. But are you meant to be using Solver? They can also be solved in a few seconds using basic algebra.

 

[MrFuz]

Welcome to the Forum!

This sounds like a homework question, where you've been asked to find the solution? Hence you "know" there is a solution?

The two equations are easily solved using Solver. But are you meant to be using Solver? They can also be solved in a few seconds using basic algebra.

Yes it can be solved using basic algebra but I’ve been tasked with using solver to find the answer, and I’m having difficulties doing so

 

[StephenCrump]

OK, thanks.

In simple terms:

- Set up adjoining cells, x and y, with some arbitrary start values
- Set up your two formula cells: = x^2 * y - 100,000, and: = 3y - 2x

In Solver, you want to:

- Set the Objective as having a value of 0 for the first formula cell,
- By changing the range containing x and y (the Variable Cells)
- Subject to the Constraint that the second formula cell must also have the value 0.

Does that work for you?

 

[MrFuz]

OK, thanks.

In simple terms:

- Set up adjoining cells, x and y, with some arbitrary start values
- Set up your two formula cells: = x^2 * y - 100,000, and: = 3y - 2x

In Solver, you want to:

- Set the Objective as having a value of 0 for the first formula cell,
- By changing the range containing x and y (the Variable Cells)
- Subject to the Constraint that the second formula cell must also have the value 0.

Does that work for you?

No, it doesn’t work. It says excel could not find a feasible solution. I have used solver before on other equations and it works but it doesn’t seem to be working for these equations. Is there a way I could send over the excel file? Or a screenshot because it says file size it too large and can’t be added

 

[StephenCrump]

To show a screenshot, you can use the XL2BB - Excel Range to BBCode add-in, so that other forum users can easily copy/paste your data and formulae. Here's my starting screenshot, for example:

	A	B	C	D	E
1
2		x	2	=x^2*y-100000	-99988
3		y	3	=3*x-2*y	0
Sheet1

Cell Formulas
Range	Formula
E2	E2	=x^2*y-100000
E3	E3	=3*x-2*y

Named Ranges
Name	Refers To	Cells
solver_adj	=Sheet1!$C$2:$C$3	E2:E3
x	=Sheet1!$C$2	E2:E3
y	=Sheet1!$C$3	E2:E3

If you want to attach a file (and it doesn't contain confidential or sensitive information) you can upload to a drop box, and post the link here. But generally, not everyone can or will want to download files, so it may limit the number of replies you get to a question if you attach files, rather than screenshots.

 

[MrFuz]

excel

Shared with Dropbox

www.dropbox.com

Im not sure how to really add add ins, I’m not that experienced with using excel. I might try XL2BB next time. Would it be possible for you to see my excel file from drop box.

 

[MrFuz]

I’ve also got these 2 equations:
10^12 = X^2 * Y
2=3*Y / X

I’m not sure what I’m doing wrong. I have no problems with solver using more simple equations but these ones don’t work with solver for me.

 

[StephenCrump]

Would it be possible for you to see my excel file from drop box.

Try starting with a positive value for x and/or y, rather than your initial start values of zero for both.