Logic of Understanding

R

Ryan$

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Jan 25, 2019
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353
To be more frankly here, I know my skills and I'm not that good much at math and LOGIC , Everyday I struggle to be better and I read more and more, but I really need your help guys and about one week something happen to me related to logic to solve the problem.
my problem is like this: I have a problem, I solve it, I arrive for instance to conclusion like this:
(1) x=y
(2)x+z=f
so once I arrive to the second equation which is x+z=f, in my head I know that's x=y, but what's confusing me is, is it legitimate to go to the first equation and afterwards going to the second equation for assigning ? I mean I know x=y, but who said that's legal to take myself to the first equation, grabbing data from their, and going with those data to the second equation and manipulate the grabbed data over the second equation?
once again, my problem isn't that I don't know that x=y or whatever, again and again, once I reach the second equation x+z=f, totally I know and still remember that x=y, but my confusion is, who said that it's legal to go to the first equation and grabbing from their the logic of the first equation, and manipulate that logic to the second equation?!!! here's totally my point!

Anyone can help me by an analogy to our real life that "manipulating LOGIC of first equation to the other equations is totally legitimate" and going, grabbing from equations and connect between them is "throughout true" and not mess the logic.

to clear more, who said it's legal to "go" from logic of first equation to manipulate it over other equations? is "going" something legal?

Sorry once again for that but I'm struggling that problem
 
Please quote the actual problem you are working on here, in its entirety. That will make all the difference. In particular, we need to see whether these are two parts of one problem, or two separate problems; and we need to see what the goal is that they are asking you to accomplish. That is what can tell you whether it is legitimate to use one in the other.

A problem you have made up or simplified from something larger is not sufficient. Until you do that, there is really nothing to say.
 
I agree with Dr. P that we need to see the specific problem to do anything concrete.

In general, however, your questions frequently seem to be about names. In the context of a given problem, whenever you assign a name to a specific concept, that name pertains to that specific mental concept throughout the problem. The x's, y's, etc. are names. If you say "Washington" means the capital of the US in a given problem, "Washington" does not come to mean the first president of the US within that problem.
 
Frankly, I can't figure out what Ryan$ is trying to say! If x= y and x+ z= f then you can say that y+ z= f because "x" and "y" are just different ways of saying the same thing. Or, from x+ z= f, x= f- z so f- z= y.
 
As I told you earlier Ryan, we can't tell what you're asking ...
 
Dr.Peterson said:
Please quote the actual problem you are working on here, in its entirety. That will make all the difference. In particular, we need to see whether these are two parts of one problem, or two separate problems; and we need to see what the goal is that they are asking you to accomplish. That is what can tell you whether it is legitimate to use one in the other.

A problem you have made up or simplified from something larger is not sufficient. Until you do that, there is really nothing to say.
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My problem that if I have two equations, for instance:
(1) x=y
(2)x+f=z
once I arrive to the second equation, while I read the first equation, I know that x=y, but not assigning that although literally I know x=y from the first equation ! so what's that problem? am I have a mentally problem? I mean is it my mentally problem, or I need to practice to start think in another way?
once again I know that I must assign x=y when I read the second equation but my mind tells me to not assign ! how can I solve that problem?>!
 
Please do what you are asked. We want to see an actual problem you found somewhere, not one that you have made up that would never be given. I can't answer you until you cooperate.
 
Dr.Peterson said:
Please do what you are asked. We want to see an actual problem you found somewhere, not one that you have made up that would never be given. I can't answer you until you cooperate.
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I do not think that there is a real problem. I think Ryan thinks that he can understand generalizations without any reference to the specifics that the generalization represents. Without understanding the generalization, he tries to do so by making up problems purportedly involving the generalization. Needless to say, you cannot dispel ignorance through ignorance.

Ryan

[MATH]x = y \text { and } x + f = z \implies y + f = z.[/MATH]
If that conclusion is helpful, you can use it.
 
Hi guys , it would be appreciated if you could help me and I really not making it hard but I face that every day. I need to fix my logic or understanding as much as I can.

sometimes I solve a question and I arrive to a conclusion that for instance in order to satisfy specific case in my question , the value of X must be zero. (it's just an example) , so what's confusing me .. why it's right to do X=0 ? I mean I know that specific case tells me that the value of X must be zero, then why I need to assign it to be zero? is the meaning of "MUST" tell me that X equal to Zero?
what's confusing me it didn't tells me explicitly that X equal to Zero .. ! it says X must be zero ..
any help to overcome that suck thinking?

thanks alot.
 
I have no idea what you are asking! You say "sometimes I solve a question and I arrive to a conclusion that for instance in order to satisfy specific case in my question , the value of X must be zero" and then ask "why it's right to do X=0?" If you are asked to solve a specific problem and find that, in order to solve the problem "X must be 0", then of course, in order to solve the problem, you must take X= 0. You might, if you wish, append "X must be 0 in order to be able to solve this problem" to your solution.

(This is like asking "If the local farmer's market is only open on Friday, why must it be Friday in order to go to the local farmer's market?")
 
HallsofIvy said:
I have no idea what you are asking! You say "sometimes I solve a question and I arrive to a conclusion that for instance in order to satisfy specific case in my question , the value of X must be zero" and then ask "why it's right to do X=0?" If you are asked to solve a specific problem and find that, in order to solve the problem "X must be 0", then of course, in order to solve the problem, you must take X= 0. You might, if you wish, append "X must be 0 in order to be able to solve this problem" to your solution.

(This is like asking "If the local farmer's market is only open on Friday, why must it be Friday in order to go to the local farmer's market?")
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thanks for your cooperation, I didn't understand your last sentence .. "(This is like asking "If the local farmer's market is only open on Friday, why must it be Friday in order to go to the local farmer's market?")" how is that related to my case which X=o or must be zero?!
 
Ryan$ said:
but I already said what's my problem .. you say no problem ! you think I'm joking? then I would burden myself to post here at all and take my time to write?
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Because, Ryan, you have been asked multiple times by multiple people to ask questions that relate to a specific problem that you have worked on. Your questions are vague and in miserable English. Frequently, the only way that we could even guess what you are talking about would be if you gave a real problem (not one of your vague "examples") and told us what is bothering you about that specific problem.

You say that you know that x = 0 is correct. You have been told many times that "=" in elementary algebra means "has the same numeric value as." So if x = 0 and you see x used in an expression (which represents a calculated numeric quantity), the expression has the same numeric value if you replace x with zero.

x = 0 and 3 + x = y means 3 + 0 = y, which in turn means 3 = y.

I suggest that if you do not understand the preceding line, you are incapable of understanding any mathematics beyond arithmetic.
 
JeffM said:
Because, Ryan, you have been asked multiple times by multiple people to ask questions that relate to a specific problem that you have worked on. Your questions are vague and in miserable English. Frequently, the only way that we could even guess what you are talking about would be if you gave a real problem (not one of your vague "examples") and told us what is bothering you about that specific problem.

You say that you know that x = 0 is correct. You have been told many times that "=" in elementary algebra means "has the same numeric value as." So if x = 0 and you see x used in an expression (which represents a calculated numeric quantity), the expression has the same numeric value if you replace x with zero.

x = 0 and 3 + x = y means 3 + 0 = y, which in turn means 3 = y.

I suggest that if you do not understand the preceding line, you are incapable of understanding any mathematics beyond arithmetic.
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Hi jeff, you see ? my problem isn't that I'm not asking question, my problem isn't understanding what the terms of math means!
thanks alot for your cooperation, I almost understand all but something still confused me , you said "you say that you know that x=0 is correct" ..here is my catch! does that mean that I must assign x=0?! who said that correct means that I can assign it?!!
 
Ryan$ said:
Hi jeff, you see ? my problem isn't that I'm not asking question, my problem isn't understanding what the terms of math means!
thanks alot for your cooperation, I almost understand all but something still confused me , you said "you say that you know that x=0 is correct" ..here is my catch! does that mean that I must assign x=0?! who said that correct means that I can assign it?!!
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Ryan, in your initial post, you said that you had deduced that x must be zero. That was the result of your own logic. So your own logic says that x = 0.

Do you know the difference between "can" and "must"? What do you mean by "assign," a word you use quite frequently?

And by "specific problem," I am not saying you did not ask a question. I am saying that you never supply the problem that raised your question. Therefore we have no context to help figure out what your question means.

x is zero and x equals zero mean the same thing in algebra. We have no idea what you are going on about with the term "assigning."

What is your native language?

Are you taking a course in a school?

How old are you?
 
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Please post an actual problem from a textbook. Then list the steps that led you to the point where you need to assign 0 to x.
 
Ryan$ said:
here's a specific example, lets assume that I'm solving that equation X^2+Y^2 =5 and by any case I concluded that X must be zero, then why must I assign X=0 to the equation X^2+Y^2 =5 ?! this is an example to the question that I asked one comment before
thanks alot
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You have essentially asked this exact question before, and it has been answered before.

If it is true that [MATH]x^2 + y^2 = 9 \text { and } x = 0[/MATH]
then you are ALLOWED to say

[MATH]x^2 + y^2 = 9 \implies 0^2 + y^2 = 9 \implies y^2 = 9 \implies y = 3 \text { or else } -\ 3.[/MATH]
No one says that you must do that. Whether doing it is useful depends on what you are trying to do. What you are trying to do depends on what problem you are trying to solve.

Please note that you have been asked numerous time to give a specific problem that has generated your question. You almost never do so. You did not do so here. You gave some specific information. You say that you know that x = 0 and that x^2 + y^2 = 5. But you have not told us how you know those things, or what you are looking for.

For each question that you pose going forward where you fail to follow our suggestion of giving the exact and complete wording of the underlying question, I shall report it as a violation of our guidelines and request that you be permanently banned for manifold and knowing violations.
 
Hi guys !
there's a lil confusing think that's struggling me and I want to how math is defining it or behind it.


if I have a which f(a)=sin^2(cos(a)) ; then if I want to assign a=5 and calculate f(a), then why immediately we are assigning a=5 into the cos without worrying on what going out of the cos? I mean if it was f(a)=a in explicitly manner then we are immediately say a=5 and I'm fine with this, but if a is under functions/operators like
sin^2(cos(a)) then can we assign a immediately however it's under operators/other functions .. if so then why? I may doesn't know the definition of assigning in math that's why ! and hope you guys help me to grasp the concept !
I know that assigns means a=5, but why for example the assigning method isn't related to what's going out/inside the function while assigning ?!


thanks alot !
 
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