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Derivative of log((x+2)/(x-2))

Function f() - derivative -N order at the point
v

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The solution

You have entered [src]
   /x + 2\
log|-----|
   \x - 2/
log(x+2x2)\log{\left(\frac{x + 2}{x - 2} \right)}
log((x + 2)/(x - 2))
Detail solution
  1. Let u=x+2x2u = \frac{x + 2}{x - 2}.

  2. The derivative of log(u)\log{\left(u \right)} is 1u\frac{1}{u}.

  3. Then, apply the chain rule. Multiply by ddxx+2x2\frac{d}{d x} \frac{x + 2}{x - 2}:

    1. Apply the quotient rule, which is:

      ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)g2(x)\frac{d}{d x} \frac{f{\left(x \right)}}{g{\left(x \right)}} = \frac{- f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}}{g^{2}{\left(x \right)}}

      f(x)=x+2f{\left(x \right)} = x + 2 and g(x)=x2g{\left(x \right)} = x - 2.

      To find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. Differentiate x+2x + 2 term by term:

        1. The derivative of the constant 22 is zero.

        2. Apply the power rule: xx goes to 11

        The result is: 11

      To find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. Differentiate x2x - 2 term by term:

        1. The derivative of the constant 2-2 is zero.

        2. Apply the power rule: xx goes to 11

        The result is: 11

      Now plug in to the quotient rule:

      4(x2)2- \frac{4}{\left(x - 2\right)^{2}}

    The result of the chain rule is:

    4(x2)(x2)2(x+2)- \frac{4 \left(x - 2\right)}{\left(x - 2\right)^{2} \left(x + 2\right)}

  4. Now simplify:

    4x24- \frac{4}{x^{2} - 4}


The answer is:

4x24- \frac{4}{x^{2} - 4}

The graph
02468-8-6-4-2-1010-2525
The first derivative [src]
        /  1      x + 2  \
(x - 2)*|----- - --------|
        |x - 2          2|
        \        (x - 2) /
--------------------------
          x + 2           
(x2)(1x2x+2(x2)2)x+2\frac{\left(x - 2\right) \left(\frac{1}{x - 2} - \frac{x + 2}{\left(x - 2\right)^{2}}\right)}{x + 2}
The second derivative [src]
/    2 + x \ /    1        1  \
|1 - ------|*|- ------ - -----|
\    -2 + x/ \  -2 + x   2 + x/
-------------------------------
             2 + x             
(1x+2x2)(1x+21x2)x+2\frac{\left(1 - \frac{x + 2}{x - 2}\right) \left(- \frac{1}{x + 2} - \frac{1}{x - 2}\right)}{x + 2}
The third derivative [src]
  /    2 + x \ /    1          1              1        \
2*|1 - ------|*|--------- + -------- + ----------------|
  \    -2 + x/ |        2          2   (-2 + x)*(2 + x)|
               \(-2 + x)    (2 + x)                    /
--------------------------------------------------------
                         2 + x                          
2(1x+2x2)(1(x+2)2+1(x2)(x+2)+1(x2)2)x+2\frac{2 \left(1 - \frac{x + 2}{x - 2}\right) \left(\frac{1}{\left(x + 2\right)^{2}} + \frac{1}{\left(x - 2\right) \left(x + 2\right)} + \frac{1}{\left(x - 2\right)^{2}}\right)}{x + 2}