Find the equation of the tangent to the curve

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Homework Help Overview

The discussion revolves around finding the equation of the tangent to the curve defined by the polynomial function y=x^3-7x^2+14x-8 at a specific point, as well as determining the x-coordinate where another tangent is parallel to the one at that point.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between the derivatives of the function at different points, specifically questioning the conditions under which the tangents are parallel.

Discussion Status

Some participants have offered guidance on the necessary conditions for the tangents to be parallel, while others are attempting to clarify their understanding of the derivative and its implications. There is an ongoing exploration of the equation that needs to be solved to find the desired x-coordinate.

Contextual Notes

Participants are working under the constraints of the problem as posed, focusing on the derivatives and the specific point of tangency without additional context or external information.

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Find the equation of the tangent to the curve y=x^3-7x^2+14x-8 at the point where x = 1. \text{Answer: }y = 3x -3
Find the x-coordinate of the point at which the tangent is parallel to the tangent at x = 1.

I need help on the second part.
 
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Well, let x* be the point you seek.
What do you know of x*?
Do you agree that we must have y'(x*)=3?
That is, the derivatives of y(x) must be equal at x=1 and x=x*
 
arildno said:
Do you agree that we must have y'(x*)=3?
Yes.
arildno said:
That is, the derivatives of y(x) must be equal at x=1 and x=x*
I think I get it. But I still don't know how to get the answer.
 
Well, do you agree that what you need to solve is the equation (written with "x"):
3=3x^{2}-14x+14
This can be rewritten as:
3(x+1)(x-1)-14(x-1)=0\to(3(x+1)-14)(x-1)=0
What must then x* be?
 
Oh! Thank you!
 

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