Math Problem Statement

Use logarithmic differentiation to find the derivative of g(x) = (sin(2x))^x.

Solution

We are tasked with using logarithmic differentiation to find the derivative of the function:

g(x)=(sin(2x))xg(x) = \left( \sin(2x) \right)^x

Step-by-Step Solution

  1. Take the natural logarithm (ln) of both sides:

    ln(g(x))=ln((sin(2x))x)\ln(g(x)) = \ln\left( (\sin(2x))^x \right)

    Using the logarithmic property ln(ab)=bln(a)\ln(a^b) = b\ln(a), this simplifies to:

    ln(g(x))=xln(sin(2x))\ln(g(x)) = x \ln(\sin(2x))

  2. Differentiate both sides with respect to xx using implicit differentiation. Keep in mind that the derivative of ln(g(x))\ln(g(x)) is g(x)g(x)\frac{g'(x)}{g(x)}.

    ddx(ln(g(x)))=ddx(xln(sin(2x)))\frac{d}{dx} \left( \ln(g(x)) \right) = \frac{d}{dx} \left( x \ln(\sin(2x)) \right)

    The left side becomes:

    g(x)g(x)\frac{g'(x)}{g(x)}

    For the right side, use the product rule: ddx(xln(sin(2x)))=ln(sin(2x))ddx(x)+xddx(ln(sin(2x)))\frac{d}{dx} \left( x \ln(\sin(2x)) \right) = \ln(\sin(2x)) \cdot \frac{d}{dx}(x) + x \cdot \frac{d}{dx}(\ln(\sin(2x))).

    This simplifies to:

    ln(sin(2x))+x1sin(2x)ddx(sin(2x))\ln(\sin(2x)) + x \cdot \frac{1}{\sin(2x)} \cdot \frac{d}{dx}(\sin(2x))

  3. Differentiate sin(2x)\sin(2x):

    ddx(sin(2x))=2cos(2x)\frac{d}{dx}(\sin(2x)) = 2\cos(2x)

    So the expression becomes:

    ln(sin(2x))+x2cos(2x)sin(2x)\ln(\sin(2x)) + x \cdot \frac{2\cos(2x)}{\sin(2x)}

  4. Substitute this result back into the equation:

    g(x)g(x)=ln(sin(2x))+2xcot(2x)\frac{g'(x)}{g(x)} = \ln(\sin(2x)) + 2x \cdot \cot(2x)

  5. Solve for g(x)g'(x):

    Multiply both sides by g(x)=(sin(2x))xg(x) = (\sin(2x))^x:

    g(x)=(sin(2x))x(ln(sin(2x))+2xcot(2x))g'(x) = (\sin(2x))^x \left( \ln(\sin(2x)) + 2x \cdot \cot(2x) \right)

Thus, the derivative of g(x)=(sin(2x))xg(x) = (\sin(2x))^x is:

g(x)=(sin(2x))x(ln(sin(2x))+2xcot(2x))g'(x) = (\sin(2x))^x \left( \ln(\sin(2x)) + 2x \cdot \cot(2x) \right)

Would you like further details or have any other questions?


Here are 5 related questions to expand on this topic:

  1. How is logarithmic differentiation useful when differentiating functions of the form f(x)g(x)f(x)^g(x)?
  2. What are some common logarithmic properties that simplify complex derivatives?
  3. How would the derivative change if the base of the power was another trigonometric function, such as cos(2x)\cos(2x)?
  4. Can logarithmic differentiation be applied to implicit functions? If yes, how?
  5. What are the differences between logarithmic differentiation and regular differentiation in terms of steps?

Tip: Logarithmic differentiation is particularly effective when both the base and the exponent are functions of xx, as it simplifies the application of the product and chain rules.

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Math Problem Analysis

Mathematical Concepts

Logarithmic Differentiation
Implicit Differentiation
Trigonometric Functions

Formulas

ln(a^b) = b ln(a)
d/dx[ln(g(x))] = g'(x)/g(x)
Product Rule: d/dx[u*v] = u'v + uv'
Chain Rule: d/dx[sin(2x)] = 2cos(2x)

Theorems

Logarithmic Differentiation Theorem
Product Rule
Chain Rule

Suitable Grade Level

Undergraduate (Calculus I or II)