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Math Help - Derivative questions.

  1. #1
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    questions in derivatives

    Hi all


    I hve two Q I want the explaine how to solve

    Q1 A) Find an equation for tangent to curve y = X^3 - 4X + 1 at the point (2,1)

    (b ) What is the range of values of the curve's slope


    Number ( A ) I can solve it but ( B) I face problem to solve



    Q 2 derivative y = x - 3root X

    please I want the explaine how to solve How to solve each one .
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  2. #2
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    Quote Originally Posted by r-soy View Post
    Hi all


    I hve two Q I want the explaine how to solve

    Q1 A) Find an equation for tangent to curve y = X^3 - 4X + 1 at the point (2,1)

    (b ) What is the range of values of the curve's slope


    Number ( A ) I can solve it but ( B) I face problem to solve



    Q 2 derivative y = x - 3root X

    please I want the explaine how to solve How to solve each one .
    Dear r-soy,

    First derivate the function, y = x^3 - 4x + 1 , and substitute x=2. Hence you will know the gradient of the straight line which touches the curve at (2,1)
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  3. #3
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    Yes , this for A

    but now what about ( B )

    ......................................

    and what about queation 2 ?

    i wait you ?
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  4. #4
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    Quote Originally Posted by r-soy View Post
    Hi all


    I hve two Q I want the explaine how to solve

    Q1 A) Find an equation for tangent to curve y = X^3 - 4X + 1 at the point (2,1)

    (b ) What is the range of values of the curve's slope


    Number ( A ) I can solve it but ( B) I face problem to solve



    Q 2 derivative y = x - 3root X

    please I want the explaine how to solve How to solve each one .

    Q1(b) the curve's slope is y' ...

    y' = 3x^2 - 4

    the range of y' is [-4,\infty)


    Q2 y = x - 3\sqrt{x}

    rewrite ...

    y = x - 3x^{\frac{1}{2}}

    use the power rule to find y'
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  5. #5
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    Thanks a lot

    How i can use the power rule to find

    I try to use

    y = 3X^1/2
    y = 1.5X^-0.5

    help me
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  6. #6
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    Quote Originally Posted by r-soy View Post
    Thanks a lot

    How i can use the power rule to find

    I try to use

    y = 3X^1/2
    y = 1.5X^-0.5 \textcolor{red}{= \frac{3}{2\sqrt{x}}}

    help me
    ...
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  7. #7
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    Quote Originally Posted by r-soy View Post
    Thanks a lot

    How i can use the power rule to find

    I try to use

    y = 3X^1/2
    y = 1.5X^-0.5

    help me
    Dear r-soy,

    The expression is y=x-3x^{\frac{1}{2}}. You have not considered the term 'x' when you derivate.

    i.e: \frac{dy}{dx}=\frac{d}{dx}x-\frac{d}{dx}(3x^{\frac{1}{2}})

    Hope this will help you.
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  8. #8
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    Hi all

    thaks for the help
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