1. **State the problem:** Find the derivative $\frac{dy}{dx}$ of the function $$y = (2 + 6x)^{\frac{5}{x}}$$ and then evaluate the slope and the value of $y$ at $x=1$.
2. **Use logarithmic differentiation:** Since the function is of the form $f(x)^{g(x)}$, take the natural logarithm of both sides:
$$\ln y = \frac{5}{x} \ln(2 + 6x)$$
3. **Differentiate both sides with respect to $x$:**
Using the chain rule on the left and product rule on the right:
$$\frac{1}{y} \frac{dy}{dx} = \frac{d}{dx} \left( \frac{5}{x} \ln(2 + 6x) \right)$$
4. **Apply the product rule:**
Let $u = \frac{5}{x}$ and $v = \ln(2 + 6x)$, then
$$\frac{d}{dx}(uv) = u'v + uv'$$
Calculate derivatives:
$$u' = -\frac{5}{x^2}$$
$$v' = \frac{6}{2 + 6x}$$
So,
$$\frac{d}{dx} \left( \frac{5}{x} \ln(2 + 6x) \right) = -\frac{5}{x^2} \ln(2 + 6x) + \frac{5}{x} \cdot \frac{6}{2 + 6x}$$
5. **Substitute back:**
$$\frac{1}{y} \frac{dy}{dx} = -\frac{5}{x^2} \ln(2 + 6x) + \frac{30}{x(2 + 6x)}$$
6. **Multiply both sides by $y$ to isolate $\frac{dy}{dx}$:**
$$\frac{dy}{dx} = y \left(-\frac{5}{x^2} \ln(2 + 6x) + \frac{30}{x(2 + 6x)} \right)$$
7. **Recall $y = (2 + 6x)^{\frac{5}{x}}$ and substitute:**
$$\frac{dy}{dx} = (2 + 6x)^{\frac{5}{x}} \left(-\frac{5}{x^2} \ln(2 + 6x) + \frac{30}{x(2 + 6x)} \right)$$
8. **Evaluate the slope at $x=1$:**
Calculate each term:
$$\ln(2 + 6 \cdot 1) = \ln(8)$$
$$y(1) = 8^{5} = 32768$$
Calculate derivative terms:
$$-\frac{5}{1^2} \ln(8) = -5 \ln(8)$$
$$\frac{30}{1 \cdot 8} = \frac{30}{8} = 3.75$$
So,
$$\frac{dy}{dx}\bigg|_{x=1} = 32768 \times (-5 \ln(8) + 3.75)$$
9. **Calculate numerical value:**
$$\ln(8) = \ln(2^3) = 3 \ln(2) \approx 3 \times 0.6931 = 2.0794$$
Then,
$$-5 \ln(8) + 3.75 = -5 \times 2.0794 + 3.75 = -10.397 + 3.75 = -6.647$$
Finally,
$$\frac{dy}{dx}\bigg|_{x=1} = 32768 \times (-6.647) \approx -217,800$$
10. **Value of $y$ at $x=1$:**
$$y(1) = 8^{5} = 32768$$
**Final answers:**
$$\frac{dy}{dx} = (2 + 6x)^{\frac{5}{x}} \left(-\frac{5}{x^2} \ln(2 + 6x) + \frac{30}{x(2 + 6x)} \right)$$
Slope at $x=1$ is approximately $$-217,800$$
Value of $y$ at $x=1$ is $$32768$$
Derivative Power Function 613E5C
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