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Find an equation of the line

  1. Oct 1, 2009 #1
    1. The problem statement, all variables and given/known data

    Function: f(x)=x^2-x Line: x+2y-6=0


    3. The attempt at a solution
    Find an equation of the line that is tangent to the graph of f and parallel to the given line.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 2, 2009 #2
    What is the requirement for two lines to be parallel to each other?
     
  4. Oct 2, 2009 #3
    First, you must simplify your line for y = mx + b form.

    x + 2y - 6 = 0

    -> x - 6 = -2y

    -> [tex]\frac{x-6}{-2}[/tex] = y

    -> y = [tex]\frac{-1x}{2}[/tex] + 3

    Next, to find a line tangent to f(x), we take it's derivitive

    f'(x) = 2x - 1

    Compare the two slopes. 2 and -1/2. These are in fact perpendicular to each other. See what you can do with that.
     
  5. Oct 2, 2009 #4

    Dick

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    Homework Helper

    I think you should rethink that. I see a line with slope -1/2 and another line with a variable slope. Perhaps you should equate them.
     
  6. Oct 4, 2009 #5
    thanks guys
     
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