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Math Help - Finding Tangent Lines

  1. #1
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    Finding Tangent Lines

    f(x) = x^2 + x + 3

    I know f ' (x) = 2x + 1.

    Now how do I find the equation of the tangent line to the curve at x = -2, or any value of x for that matter
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  2. #2
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    I suck at explaining this but this may help you to "see" what the tangent line is:
    Tangent - Wikipedia, the free encyclopedia
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  3. #3
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    equation of the tangenet line to the function f at x=a is :
    y-f(a)=f`(a) (x-a)
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by TWiX View Post
    equation of the tangenet line to the function f at x=a is :
    y-f(a)=f'(a) (x-a)
    this is correct

    Hopefully you understand where this comes from, Zabulius. In particular, you should be aware that the derivative gives a formula for finding the slope at any value of x for a particular function. the tangent line is a straight line, and is hence of the form y = mx + b where m is the slope (hence given by the derivative) and b is the y-intercept. once you find the slope and a point the line passes through (this is the point (a, f(a)) in the above formula) you can find the equaiton of the line
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  5. #5
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    Thanks to everyone for the help. I'm pretty sure I did a decent job on my exam this morning.
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