Mister Exam

Derivative of 3log2(x)(4x+5)-6x

Function f() - derivative -N order at the point
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The graph:

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Piecewise:

The solution

You have entered [src]
  log(x)                
3*------*(4*x + 5) - 6*x
  log(2)                
6x+3log(x)log(2)(4x+5)- 6 x + 3 \frac{\log{\left(x \right)}}{\log{\left(2 \right)}} \left(4 x + 5\right)
(3*(log(x)/log(2)))*(4*x + 5) - 6*x
Detail solution
  1. Differentiate 6x+3log(x)log(2)(4x+5)- 6 x + 3 \frac{\log{\left(x \right)}}{\log{\left(2 \right)}} \left(4 x + 5\right) term by term:

    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)=3(4x+5)log(x)f{\left(x \right)} = 3 \left(4 x + 5\right) \log{\left(x \right)} and g(x)=log(2)g{\left(x \right)} = \log{\left(2 \right)}.

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

      1. The derivative of a constant times a function is the constant times the derivative of the function.

        1. Apply the product rule:

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

          f(x)=4x+5f{\left(x \right)} = 4 x + 5; to find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

          1. Differentiate 4x+54 x + 5 term by term:

            1. The derivative of the constant 55 is zero.

            2. The derivative of a constant times a function is the constant times the derivative of the function.

              1. Apply the power rule: xx goes to 11

              So, the result is: 44

            The result is: 44

          g(x)=log(x)g{\left(x \right)} = \log{\left(x \right)}; to find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

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

          The result is: 4log(x)+4x+5x4 \log{\left(x \right)} + \frac{4 x + 5}{x}

        So, the result is: 12log(x)+3(4x+5)x12 \log{\left(x \right)} + \frac{3 \left(4 x + 5\right)}{x}

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

      1. The derivative of the constant log(2)\log{\left(2 \right)} is zero.

      Now plug in to the quotient rule:

      12log(x)+3(4x+5)xlog(2)\frac{12 \log{\left(x \right)} + \frac{3 \left(4 x + 5\right)}{x}}{\log{\left(2 \right)}}

    2. The derivative of a constant times a function is the constant times the derivative of the function.

      1. Apply the power rule: xx goes to 11

      So, the result is: 6-6

    The result is: 12log(x)+3(4x+5)xlog(2)6\frac{12 \log{\left(x \right)} + \frac{3 \left(4 x + 5\right)}{x}}{\log{\left(2 \right)}} - 6

  2. Now simplify:

    12log(x)log(2)6+12log(2)+15xlog(2)\frac{12 \log{\left(x \right)}}{\log{\left(2 \right)}} - 6 + \frac{12}{\log{\left(2 \right)}} + \frac{15}{x \log{\left(2 \right)}}


The answer is:

12log(x)log(2)6+12log(2)+15xlog(2)\frac{12 \log{\left(x \right)}}{\log{\left(2 \right)}} - 6 + \frac{12}{\log{\left(2 \right)}} + \frac{15}{x \log{\left(2 \right)}}

The graph
02468-8-6-4-2-1010-500500
The first derivative [src]
     12*log(x)   3*(4*x + 5)
-6 + --------- + -----------
       log(2)      x*log(2) 
12log(x)log(2)6+3(4x+5)xlog(2)\frac{12 \log{\left(x \right)}}{\log{\left(2 \right)}} - 6 + \frac{3 \left(4 x + 5\right)}{x \log{\left(2 \right)}}
The second derivative [src]
  /    5 + 4*x\
3*|8 - -------|
  \       x   /
---------------
    x*log(2)   
3(84x+5x)xlog(2)\frac{3 \left(8 - \frac{4 x + 5}{x}\right)}{x \log{\left(2 \right)}}
The third derivative [src]
  /     5 + 4*x\
6*|-6 + -------|
  \        x   /
----------------
    2           
   x *log(2)    
6(6+4x+5x)x2log(2)\frac{6 \left(-6 + \frac{4 x + 5}{x}\right)}{x^{2} \log{\left(2 \right)}}