Write symbolically: negation and useful denial

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Homework Help Overview

The problem involves expressing the intersection of two curves, y = 1−x² and y = 3x-2, symbolically, including quantification of variables and negation of the statement in natural language. The context is within the realm of algebra and set theory.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss how to express the curves symbolically and consider using set notation for the intersection. Questions arise about whether to equate the curves directly or to represent them as sets.

Discussion Status

Some participants have offered guidance on using set notation to represent the curves, while others express uncertainty about their understanding of sets. There is acknowledgment that the problem can be approached in multiple ways, but no consensus has been reached on the best method.

Contextual Notes

One participant notes that they have not yet learned how to work with sets, which may limit their approach. There is also mention that the statement about the intersection does not need to be true, indicating a focus on formal expression rather than solving the equations.

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Homework Statement


Express the statement symbolically, including a quantification of all variables which makes the universe explicit. Negate the symbolic statement, and express the negation in natural language as a useful denial.

The curves y = 1−x2 and y = 3x-2 intersect.

2. Homework Equations

The Attempt at a Solution


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I am unsure of how to write this statement symbolically.

I assume I start with (∃x∈U) since there is only two point of intersections.

However I do not know where to go from there.

Would I have to equate them to each other?

Would doing 1−x2 = 3x-2 be correct?

Thank you.
 
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I would start to write the curves as sets and consider pairs ##(x,y)\in U## not only ##x##:
##P:=\{\,(x,y)\,:\,y+x^2-1=0\,\}## and ##S:=\{\,(x,y)\,:\,y-3x+2=0\,\}##. This way you can handle the intersection as intersection of sets.
 
fresh_42 said:
I would start to write the curves as sets and consider pairs ##(x,y)\in U## not only ##x##:
##P:=\{\,(x,y)\,:\,y+x^2-1=0\,\}## and ##S:=\{\,(x,y)\,:\,y-3x+2=0\,\}##. This way you can handle the intersection as intersection of sets.
Thank you for the help, I have not yet learned how to work in sets but I will try to complete my answer using this way. But could this question also be completed if they were to be equated to each other?
 
ver_mathstats said:
Thank you for the help, I have not yet learned how to work in sets but I will try to complete my answer using this way. But could this question also be completed if they were to be equated to each other?
You can solve it this way, but a solution is not requested, only a formal statement about the set of solutions. The statement does not have to be true, but unfortunately they do intersect. But again, a statement about a solution is something else than the actual solution. So even if you write it as ##x^2+3x-3=0## then you still have to say something about the solution of this quadratic equation.
 

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