Finding Horizontal Tangent Lines on a Parabola

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SUMMARY

The discussion focuses on finding horizontal tangent lines for the parabola defined by the function f(x) = x² - 4x + 5. The key conclusion is that the horizontal tangent occurs at the vertex of the parabola, which can be determined by completing the square. The specific value of x where the tangent line is horizontal is x = 2, corresponding to the vertex of the parabola.

PREREQUISITES
  • Understanding of quadratic functions and their properties
  • Knowledge of completing the square technique
  • Familiarity with the concept of tangent lines in calculus
  • Basic graphing skills for parabolas
NEXT STEPS
  • Study the process of completing the square for quadratic equations
  • Learn about finding derivatives to determine tangent lines
  • Explore the properties of parabolas, including vertex and axis of symmetry
  • Investigate the relationship between a function and its inverse in terms of graphing
USEFUL FOR

Students studying algebra and calculus, particularly those focusing on quadratic functions and their graphical properties.

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Homework Statement



I have a homework that i couldn't do :( can you explain it to me please ?
the problem is :
find all values of x=c so that the tangent line to the graph of f(x) af (c , f(c)) will be horizontal
http://img13.imageshack.us/img13/4222/scan0002izs.jpg





The Attempt at a Solution


i know in the end the answer will be x = 2 ... but i want to how did we get it
 
Last edited by a moderator:
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Consider y = x2 - 4x + 5.

The graph of this equation is a parabola that opens up. By completing the square you can find the vertex and the coordinates of the vertex. The tangent line to this graph is horizontal at the vertex.

The function you have is related to this in that all of its y-values are the square roots of the y-values on the parabola.

Hope this is enough of a hint.
Mark
 

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