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Solving equation/finding relation with ">" - HELP

mdruedahl
1-Visitor

Solving equation/finding relation with ">" - HELP

I am having some troubles solving the following equation. I have some trouble understanding the answer and what i need to do, to get a valid result?

help+is+wanted.PNG

ACCEPTED SOLUTION

Accepted Solutions
Werner_E
25-Diamond I
(To:mdruedahl)

You should attach your worksheet, not just a pic.

I guess you recognize the symbols for AND and OR. Mathcad has to consider all possibilities it has to cope with the event of two variables being the same and so we are not allowed to devide by their difference. Furthermore some variables may be complex and so can't be "ordered" (you can't decide which one is greater).

So the solution you probably have expected, the expression in front of the second line of Mathcads solution, is not valid in every case and thats what Mathcad is telling you.

Do you really need a full symbolic solution? You may try the symbolic solve coupled with a series of assumes, telling MC that certain or all variables are real, are positive, a certain difference never will be zero, and whatever assumptions you may make implicitely if you solve by hand.

Best thing would be to delete that additional constraint as its irrelevant anyway without knowing anything about the other variables. Guess you will get the desired result that way.

26.02.png

View solution in original post

1 REPLY 1
Werner_E
25-Diamond I
(To:mdruedahl)

You should attach your worksheet, not just a pic.

I guess you recognize the symbols for AND and OR. Mathcad has to consider all possibilities it has to cope with the event of two variables being the same and so we are not allowed to devide by their difference. Furthermore some variables may be complex and so can't be "ordered" (you can't decide which one is greater).

So the solution you probably have expected, the expression in front of the second line of Mathcads solution, is not valid in every case and thats what Mathcad is telling you.

Do you really need a full symbolic solution? You may try the symbolic solve coupled with a series of assumes, telling MC that certain or all variables are real, are positive, a certain difference never will be zero, and whatever assumptions you may make implicitely if you solve by hand.

Best thing would be to delete that additional constraint as its irrelevant anyway without knowing anything about the other variables. Guess you will get the desired result that way.

26.02.png

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