Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: This is a true statement right?

  1. Sep 8, 2007 #1
    If [tex]f(x)=x^3-6x+c_2[/tex] and I know that [tex]y=5-3x[/tex] is tangent at the point where x=1,
    then I can say that at x=1 [tex]f(x)=x^3-6x+c_2|_{x=1}=5-3x.[/tex]
    Right? and then I can solve for [tex]c_2[/tex]

    I am getting the correct answer to my text problem, but I want to be sure that it is because my reasoning is correct.

  2. jcsd
  3. Sep 8, 2007 #2


    User Avatar
    Science Advisor

    I presume that by "[tex]f(x)=x^3-6x+c_2|_{x=1}[/tex]", you mean f(1).
    Your reasoning is correct but I would write f(1)= 13- 6(1)+ c2= 5- 3(1).
  4. Sep 8, 2007 #3
    I guess that is a shorter hand way of writing it. But I guess I wanted to be sure that it was indeed f(x)=y at x=1. That the function and the equation were equivalent.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook