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Math Help - equation of "normal line"

  1. #1
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    equation of "normal line"

    hi i got this question :

    give the equation of the normal line to the graph of y=2x SQRT(x^2+8) + 2.
    at the point (0,2)

    what are they asking me? what is the equation of the normal line? I was like, are they asking me for mx+b form of this or something? because none of the answers have a form like that.

    the answers are :
    a) x-4 sqrt(2) y = -8 sqrt(2)
    b) x+4 sqrt(2) y = 8 sqrt(2)
    c)4 sqrt(2)x + y = 2
    d)-4 sqrt(2)x + y = 2
    e) x+4 sqrt(2)y = 2

    PS how do I write math with html so it looks readable like you pro posters do?
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  2. #2
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    They are asking you to find the derivative at that point and then to give the equation of a tangent line I believe. So once you do so your answer will look something like one of those answers.

    Latex is what I believe most people use, and it takes a little getting used to from what I gather, but there's a section for it in the forum.
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  3. #3
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    Quote Originally Posted by eulcer View Post
    They are asking you to find the derivative at that point and then to give the equation of a tangent line I believe.
    no ... a normal line is the line perpendicular to the tangent line at the point of tangency.
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  4. #4
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    why do they call it the normal line?
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  5. #5
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    Quote Originally Posted by frankinaround View Post
    why do they call it the normal line?
    norˇmal (nôrml)
    adj. 1. Conforming with, adhering to, or constituting a norm, standard, pattern, level, or type; typical: normal room temperature; one's normal weight; normal diplomatic relations.
    2. Biology Functioning or occurring in a natural way; lacking observable abnormalities or deficiencies.
    3. Abbr. n or N Chemistry
    a. Designating a solution having one gram equivalent weight of solute per liter of solution.
    b. Designating an aliphatic hydrocarbon having a straight and unbranched chain of carbon atoms.
    4. Mathematics
    a. Being at right angles; perpendicular.
    b. Perpendicular to the direction of a tangent line to a curve or a tangent plane to a surface.

    5.
    a. Relating to or characterized by average intelligence or development.
    b. Free from mental illness; sane.

    n. 1. Something normal; the standard: scored close to the normal.
    2. The usual or expected state, form, amount, or degree.
    3.
    a. Correspondence to a norm.
    b. An average.
    4. Mathematics A perpendicular, especially a perpendicular to a line tangent to a plane curve or to a plane tangent to a space curve.
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