To find the derivative of \(\frac{5x}{x^5}\) with respect to \(x\), first simplify the expression:
\(\frac{5x}{x^5} = 5x^1 \cdot x^{-5} = 5x^{1-5} = 5x^{-4}\)
Next, apply the power rule (\(\frac{d}{dx}[x^n] = n x^{n-1}\)) to differentiate \(5x^{-4}\):
\(\frac{d}{dx}[5x^{-4}] = 5 \cdot (-4) x^{-4-1} = -20x^{-5}\)
The resulting derivative is \(-20x^{-5}\), which can also be written as \(\frac{-20}{x^5}\).
If $e^y (x+1) = 1$, then find the value of $$ \frac{d^2 y}{dx^2} - \left(\frac{dy}{dx}\right)^2. $$