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Math Help - Just need a little help on these questions. :)

  1. #1
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    Just need a little help on these questions. :)

    1. The curve C is given by the equation y=mx3-x2+8x+2, for a constant m
    A) find dy/dx

    The point P lies on C, and has the x-value 5
    The normal to C at P is parallel to the line given by the equation y+4x-3=0.

    B)find the gradient of the curve at C at P.

    Hence find:
    C) (I) the value of m,

    (ii) the y-value at p.

    Just really stuck on this question any help would be brilliant
    Thanks.
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  2. #2
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    Re: Just need a little help on these questions. :)

    please post calculus problems in the calculus forum ... the lobby is for introductions.
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  3. #3
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    Re: Just need a little help on these questions. :)

    Quote Originally Posted by Walshy4119 View Post
    1. The curve C is given by the equation y=mx3-x2+8x+2, for a constant m
    A) find dy/dx
    Okay, what did you get for dy/dx?

    The point P lies on C, and has the x-value 5
    So what are y and dy/dx when x= 5?

    The normal to C at P is parallel to the line given by the equation y+4x-3=0.
    Are you asked to find m so that this is true? The slope of a line perpendicular to a curve, y= f(x), is equal to -1/f'(x). What is the slope of the line y+ 4x- 3= 0?

    Find the gradient of the curve at C at P.
    Okay, that is dy/dx evaluated at x= 5.

    Hence find:
    C) (I) the value of m,

    (ii) the y-value at p.

    Just really stuck on this question any help would be brilliant
    Thanks.[/QUOTE]
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  4. #4
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    Re: Just need a little help on these questions. :)

    Sorry i posted on the wrong page I'll post it properly now.
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