y=x^3 + 2x using dy/dx?

Using the formula y=x^3 + 2x, I am to using deriatives, find the equation of the tangent line. Any help would be appreciated!

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  • 1 decade ago
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    equation of the tangent of the line is the derivative of the line

    dy/dx = 3x^2 + 2

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  • 1 decade ago

    dy/dx = 3x^2 + 2.

    The equation of a line is (y-y1) = m(x-x1)

    So, the find the tangent line going through x1=a:

    y1 = a^3 + 2a

    m = 3a^2 + 2

    So y - (a^3 + 2a) = (3a^2 + 2)(x-a).

    You could expand and rearrange if you want.

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  • 1 decade ago

    (dy/dx) = (3 x^2 )+ 2

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