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Math Help - tangent lines

  1. #1
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    tangent lines

    hey i need some help with tangent lines, i just dont understand it at all. I need to figure out how to find the equation of the tangent line to f(x)=x^3 at the point where x=3...much thanks
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    Quote Originally Posted by mer1988 View Post
    hey i need some help with tangent lines, i just dont understand it at all. I need to figure out how to find the equation of the tangent line to f(x)=x^3 at the point where x=3...much thanks
    remember, a line is of the form y = mx + b where m is the slope, and b is the y-intercept.

    how do we find the slope? well, from the derivative of course. find y' and plug in x = 3 to get the slope at that point, then use the point slope form.

    y = y_1 = m(x - x_1)

    where (x_1,y_1) is the point on the graph when x = 3

    just solve for y to get the equation of the line
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