12. If y=x, then y' is.. (HINT: Use logarithmic differentiation.)

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### Calculus Problem – Logarithmic Differentiation

**Problem:**

12. If \( y = x^{\ln x} \), then \( y' \) is...
(Hint: Use logarithmic differentiation.)

**Solution:**

To solve this problem, we'll use the technique of logarithmic differentiation. Logarithmic differentiation is especially useful when you have a function in the form of one variable raised to another variable. Here, we proceed with the following steps:

1. **Take the Natural Logarithm of Both Sides:**

   Given:
   \[
   y = x^{\ln x}
   \]

   Taking the natural logarithm (ln) of both sides:
   \[
   \ln y = \ln (x^{\ln x})
   \]

2. **Simplify Using Logarithm Properties:**

   Use the property of logarithms that \(\ln(a^b) = b \ln a\):
   \[
   \ln y = \ln x \cdot \ln x
   \]
   \[
   \ln y = (\ln x)^2
   \]

3. **Differentiate Both Sides with Respect to \(x\):**

   Recall that \(\frac{d}{dx} (\ln y) = \frac{1}{y} \cdot y'\):
   \[
   \frac{1}{y} \cdot y' = \frac{d}{dx}((\ln x)^2)
   \]

   Using the chain rule on the right-hand side:
   \[
   \frac{1}{y} \cdot y' = 2 \ln x \cdot \frac{1}{x}
   \]
   \[
   \frac{1}{y} \cdot y' = \frac{2 \ln x}{x}
   \]

4. **Solve for \( y' \):**

   Multiply both sides by \( y \):
   \[
   y' = y \cdot \frac{2 \ln x}{x}
   \]

5. **Substitute \( y \) Back into the Expression:**

   Recall that \( y = x^{\ln x} \):
   \[
   y' = x^{\ln x} \cdot \frac{2 \ln x}{x}
   \]

   Simplify further:
   \[
Transcribed Image Text:### Calculus Problem – Logarithmic Differentiation **Problem:** 12. If \( y = x^{\ln x} \), then \( y' \) is... (Hint: Use logarithmic differentiation.) **Solution:** To solve this problem, we'll use the technique of logarithmic differentiation. Logarithmic differentiation is especially useful when you have a function in the form of one variable raised to another variable. Here, we proceed with the following steps: 1. **Take the Natural Logarithm of Both Sides:** Given: \[ y = x^{\ln x} \] Taking the natural logarithm (ln) of both sides: \[ \ln y = \ln (x^{\ln x}) \] 2. **Simplify Using Logarithm Properties:** Use the property of logarithms that \(\ln(a^b) = b \ln a\): \[ \ln y = \ln x \cdot \ln x \] \[ \ln y = (\ln x)^2 \] 3. **Differentiate Both Sides with Respect to \(x\):** Recall that \(\frac{d}{dx} (\ln y) = \frac{1}{y} \cdot y'\): \[ \frac{1}{y} \cdot y' = \frac{d}{dx}((\ln x)^2) \] Using the chain rule on the right-hand side: \[ \frac{1}{y} \cdot y' = 2 \ln x \cdot \frac{1}{x} \] \[ \frac{1}{y} \cdot y' = \frac{2 \ln x}{x} \] 4. **Solve for \( y' \):** Multiply both sides by \( y \): \[ y' = y \cdot \frac{2 \ln x}{x} \] 5. **Substitute \( y \) Back into the Expression:** Recall that \( y = x^{\ln x} \): \[ y' = x^{\ln x} \cdot \frac{2 \ln x}{x} \] Simplify further: \[
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