Math Problem Statement

Differentiate g(x) = ln((7-x)/(7+x)).

Solution

To differentiate the function g(x)=ln(7x7+x)g(x) = \ln\left( \frac{7 - x}{7 + x} \right), we can use the chain rule and the derivative properties of the natural logarithm.

Steps:

  1. Let u=7x7+xu = \frac{7 - x}{7 + x}.
  2. Then, g(x)=ln(u)g(x) = \ln(u).
  3. The derivative of g(x)g(x) with respect to xx is given by g(x)=1ududxg'(x) = \frac{1}{u} \cdot \frac{du}{dx}.

Now we need to find dudx\frac{du}{dx}.

Finding dudx\frac{du}{dx}:

u=7x7+xu = \frac{7 - x}{7 + x} We can use the quotient rule, where if u=f(x)g(x)u = \frac{f(x)}{g(x)}, then: dudx=f(x)g(x)f(x)g(x)[g(x)]2\frac{du}{dx} = \frac{f'(x)g(x) - f(x)g'(x)}{[g(x)]^2}

Here, f(x)=7xf(x) = 7 - x and g(x)=7+xg(x) = 7 + x.

  • f(x)=1f'(x) = -1
  • g(x)=1g'(x) = 1

Applying the quotient rule: dudx=(1)(7+x)(7x)(1)(7+x)2=7x7+x(7+x)2=14(7+x)2\frac{du}{dx} = \frac{(-1)(7 + x) - (7 - x)(1)}{(7 + x)^2} = \frac{-7 - x - 7 + x}{(7 + x)^2} = \frac{-14}{(7 + x)^2}

Now, substituting back:

g(x)=17x7+x14(7+x)2g'(x) = \frac{1}{\frac{7 - x}{7 + x}} \cdot \frac{-14}{(7 + x)^2}

Simplify further: g(x)=7+x7x14(7+x)2g'(x) = \frac{7 + x}{7 - x} \cdot \frac{-14}{(7 + x)^2}

g(x)=14(7x)(7+x)g'(x) = \frac{-14}{(7 - x)(7 + x)}

Finally, we get: g(x)=1449x2g'(x) = \frac{-14}{49 - x^2}

So, the derivative g(x)=1449x2g'(x) = \frac{-14}{49 - x^2}.

Do you want more details or have any questions?

Related Questions:

  1. How do you find the derivative of a logarithmic function involving a different base?
  2. What is the chain rule in calculus, and when is it used?
  3. How can we differentiate a function involving trigonometric expressions?
  4. What are the common properties of logarithms useful in differentiation?
  5. How would you integrate the function g(x)g'(x) to find the original g(x)g(x)?

Tip: Always simplify the argument inside the logarithm before differentiating, if possible, to make the differentiation process easier.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Natural Logarithm
Quotient Rule
Chain Rule

Formulas

g'(x) = 1/u * du/dx
u = (7-x)/(7+x)
du/dx = (f'(x)g(x) - f(x)g'(x)) / [g(x)]^2

Theorems

Quotient Rule
Chain Rule

Suitable Grade Level

Undergraduate Calculus