Derivation, absolute value problem

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Homework Help Overview

The problem involves finding the value of k such that the line y - 36x = k is a normal to the curve defined by y = 1 / abs(x-2). The discussion centers around the implications of the absolute value in the context of the curve's behavior and its derivatives.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between the tangent and normal lines to the curve, particularly focusing on the sign of the tangent and how it relates to the absolute value term. Questions arise about the implications of the graph of the absolute value function and its derivative.

Discussion Status

The discussion is ongoing, with participants exploring the graphical representation of the absolute value function and its derivatives. There is an acknowledgment of the need to understand the behavior of the curve before proceeding with algebraic methods.

Contextual Notes

Participants note that the behavior of the curve changes at x = 2, which is relevant for determining the sign of the absolute value term. There is a focus on the derivative's sign in relation to the curve's characteristics.

Kqwert
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Homework Statement


Find k so that y - 36x = k is a normal to the curve y = 1 / abs(x-2).

Homework Equations

The Attempt at a Solution


My problem is regarding the absolute value. I know that the tangent to the curve must be (-1/36). In the solutions manual, it is said that by knowing the sign of the tangent (i.e. negative) we can know the sign of the absolute value term. How is this possible?
 
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Kqwert said:

Homework Statement


Find k so that y - 36x = k is a normal to the curve y = 1 / abs(x-2).

Homework Equations

The Attempt at a Solution


My problem is regarding the absolute value. I know that the tangent to the curve must be (-1/36). In the solutions manual, it is said that by knowing the sign of the tangent (i.e. negative) we can know the sign of the absolute value term. How is this possible?
Have you drawn a graph of the absolute value function?
 
PeroK said:
Have you drawn a graph of the absolute value function?
Yes I have, but not sure exactly what I know by doing that. Or, I guess I can see that x must be larger than 2, because that is the only place of the curve where it has a negative derivative? And therefore I know that the absolute value sign is positive...?
 
Kqwert said:
Yes I have, but not sure exactly what I know by doing that. Or, I guess I can see that x must be larger than 2, because that is the only place of the curve where it has a negative derivative? And therefore I know that the absolute value sign is positive...?

I think that's the idea. You can see from the graph before you start any algebra what solution approx you are looking for.
 
Last edited:

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