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Math Help - Equation of a horizontal tangent line..

  1. #1
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    Equation of a horizontal tangent line..

    Let f be the function defined by f(x)=3x^5-5x^3+2


    How would I find the horizontal tangent line..? ><"
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    Quote Originally Posted by MadHotThunder View Post
    Let f be the function defined by f(x)=3x^5-5x^3+2


    How would I find the horizontal tangent line..? ><"
    The tangent to the curve is horizontal at the stationary points.

    So you need to calculate the y-coordinate of all stationary points. I suggest using calculus to first get the x-coordinates.
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    I don't quite understand.
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    Quote Originally Posted by MadHotThunder View Post
    I don't quite understand.
    Find the y-coordinates of the stationary points. Can you do that?
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    nope.
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    Quote Originally Posted by MadHotThunder View Post
    nope.
    Start by finding the x-coordinates of the stationary points. Can you do that?
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    If by stationary points you mean critical numbers, I have x=0 and x=+1
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    Quote Originally Posted by MadHotThunder View Post
    If by stationary points you mean critical numbers, I have x=0 and x=+1
    Good. Now substitute these values into y = f(x) to get the y-coordinates of the critical points.
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    Quote Originally Posted by mr fantastic View Post
    Good. Now substitute these values into y = f(x) to get the y-coordinates of the critical points.
    (0,2) (1,0) and (-1, 4)
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    Quote Originally Posted by MadHotThunder View Post
    (0,2) (1,0) and (-1, 4)
    Good. So the horizontal tangents have equation y = 2, y = ..... and .....
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    y=2, y=4, and y=0?
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    Quote Originally Posted by MadHotThunder View Post
    y=2, y=4, and y=0?
    Yes.
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    Quote Originally Posted by mr fantastic View Post
    Yes.

    Thank you so muchhh.
    It's kind of a dumb question, and I really appreciate your patience with me.
    I've been working on calculus since I got out of school today. u___u
    Again, thanks so much.
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  14. #14
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    Quote Originally Posted by MadHotThunder View Post
    Thank you so muchhh.
    It's kind of a dumb question, and I really appreciate your patience with me.
    I've been working on calculus since I got out of school today. u___u
    Again, thanks so much.
    It's a pleasure helping someone who's willing to be guided to the answer.
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