Relationship between roots and coefficients

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Homework Help Overview

The discussion revolves around the relationship between the roots and coefficients of a polynomial, particularly focusing on a fourth-degree polynomial and its roots. Participants are exploring the conditions under which curves represented by equations intersect and touch each other, with specific reference to points of tangency.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss solving equations simultaneously to find points of intersection and question the implications of these points being tangential. There is an exploration of how to prove tangency given limited information, such as only having x-values for the points. Others raise questions about the maximum number of real roots a fourth-degree polynomial can have and the nature of double roots.

Discussion Status

The discussion is active, with participants sharing their attempts and questioning assumptions about tangency and the nature of polynomial roots. Some guidance has been offered regarding the implications of intersection points, but no consensus has been reached on how to prove the tangency or fully resolve the problem.

Contextual Notes

Participants are working within the constraints of pre-calculus concepts and are attempting to understand the geometric implications of polynomial roots and their relationships to curves. There is an acknowledgment of the complexity involved in proving tangency with limited data.

aanandpatel
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Homework Statement



SCAN0341.jpg


Homework Equations



Sum of roots taken one at a time is -b/a
Sum of roots taken two at a time is c/a
three at a time is -d/a
four at a time is e/a

The Attempt at a Solution


I did part one by solving the two equations simultaneously.
For part two, I said that it has those roots because that is where the two curves touch
I'm stuck on part three - tried to solve it by applying the above equations and eliminating \gamma and \delta since they are equal to \alpha and \beta respectively but this did not work.
Help would be greatly appreciated :)
 
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aanandpatel said:

Homework Statement



Homework Equations



Sum of roots taken one at a time is -b/a
Sum of roots taken two at a time is c/a
three at a time is -d/a
four at a time is e/a

The Attempt at a Solution


I did part one by solving the two equations simultaneously.
For part two, I said that it has those roots because that is where the two curves touch
I'm stuck on part three - tried to solve it by applying the above equations and eliminating \gamma and \delta since they are equal to \alpha and \beta respectively but this did not work.
Help would be greatly appreciated :)

For (i). Solving the equations simultaneously only means that the points satisfying that equation are on both the circle and one hyperbola. It doesn't mean that such points occur where the curves are tangent to each other.

Since this is in the pre-calculus section, I ask, do you know how to show that the points of intersection are points of tangency ?
 
The question says that the curves touch at the points A and B so I assumed they were tangential to each other at those points. Not sure how I would prove it otherwise seeing as I only have an x value for the points.
 
It's possible for these curves to intersect in as many as 4 points. The fact that they intersect (touch) at only two points is a hint to answering question ii .

How many real roots can a degree 4 polynomial have in general ?
 
a fourth degree polynomial has 4 roots therefore alpha and beta are double roots?
 

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