Derivative Second 51004E
1. We are asked to find the first and second derivatives of the function $$f(x) = \frac{1}{2 + \sin x}$$.
2. The first derivative of a function of the form $$\frac{1}{g(x)}$$ is given by the chain rule and quotient rule as:
$$f'(x) = -\frac{g'(x)}{(g(x))^2}$$
where $$g(x) = 2 + \sin x$$.
3. Calculate $$g'(x)$$:
$$g'(x) = \cos x$$
4. Substitute into the formula for $$f'(x)$$:
$$f'(x) = -\frac{\cos x}{(2 + \sin x)^2}$$
5. Now, find the second derivative $$f''(x)$$ by differentiating $$f'(x)$$:
$$f''(x) = \frac{d}{dx} \left(-\frac{\cos x}{(2 + \sin x)^2}\right)$$
6. Use the quotient rule or product rule with chain rule. Let:
$$u = -\cos x$$ and $$v = (2 + \sin x)^{-2}$$
7. Differentiate $$u$$ and $$v$$:
$$u' = \sin x$$
$$v' = -2(2 + \sin x)^{-3} \cdot \cos x$$ (by chain rule)
8. Apply product rule:
$$f''(x) = u'v + uv' = \sin x (2 + \sin x)^{-2} + (-\cos x) \left(-2(2 + \sin x)^{-3} \cos x\right)$$
9. Simplify:
$$f''(x) = \frac{\sin x}{(2 + \sin x)^2} + \frac{2 \cos^2 x}{(2 + \sin x)^3}$$
10. This is the second derivative of the function.
Final answers:
$$f'(x) = -\frac{\cos x}{(2 + \sin x)^2}$$
$$f''(x) = \frac{\sin x}{(2 + \sin x)^2} + \frac{2 \cos^2 x}{(2 + \sin x)^3}$$