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# 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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- ludacrusherLv 41 decade agoFavorite Answer
equation of the tangent of the line is the derivative of the line

dy/dx = 3x^2 + 2

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- stephen mLv 41 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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