Newtons Method Root Dab5Ac
1. The problem asks for the expression of $x_{n+1}$ in Newton's Method to find the root of the function $$f(x) = \cos x (x^2 + 2x + 2).$$
2. Newton's Method formula is:
$$x_{n+1} = x_n - \frac{f(x_n)}{f'(x_n)}$$
3. First, find the derivative $f'(x)$ using the product rule:
$$f(x) = u(x)v(x) \text{ where } u(x) = \cos x, v(x) = x^2 + 2x + 2$$
4. Derivative of $u(x)$:
$$u'(x) = -\sin x$$
5. Derivative of $v(x)$:
$$v'(x) = 2x + 2$$
6. Using product rule:
$$f'(x) = u'(x)v(x) + u(x)v'(x) = -\sin x (x^2 + 2x + 2) + \cos x (2x + 2)$$
7. Substitute $f(x)$ and $f'(x)$ into Newton's formula:
$$x_{n+1} = x_n - \frac{\cos x_n (x_n^2 + 2x_n + 2)}{-\sin x_n (x_n^2 + 2x_n + 2) + \cos x_n (2x_n + 2)}$$
8. Simplify the denominator sign:
$$x_{n+1} = x_n - \frac{\cos x_n (x_n^2 + 2x_n + 2)}{\cos x_n (2x_n + 2) - \sin x_n (x_n^2 + 2x_n + 2)}$$
9. This matches option C:
$$x_{n+1} = x_n - \frac{\cos x (x^2 + 2x + 2)}{\cos x (2x + 2) - \sin x (x^2 + 2x + 2)}$$
Final answer: Option C.