JESS asked in 科學及數學數學 · 1 decade ago

Derivative- Normal line(急!!!)

我想知...

find the equation for the normal line to F(x) at x=4

係用咩式同有咩step計佢出泥

thx~

1 Answer

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  • 1 decade ago
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    搵normal既話,要先搵slope of tangent

    既然我唔知個function係咩,我唯有用F'(x)繼續做落去.

                  y = F(x)

            slope of tangent = F'(x)

    As tangent ⊥ normal,

    slope of tangent * slope of normal = -1

         F'(x) * slope of normal = -1

           slope of normal = -1 / F'(x)

    slope of normal line to F(x) at x=4 = -1 / F'(4)

    Then, the equation for the normal line to F(x) at x=4 is

         [ y - F(4) ] / ( x - 4) = -1 / F'(4)

         F'(4)y - F(4) F'(4) = - x + 4

             x + F'(4)y = F(4) F'(4) + 4 //

    Source(s): by My Maths
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