1. **Problem statement:** Given the function $f(x) = x^3 - 3x^2 + 3$,
(a) Find the equation of the tangent line at the inflection point.
(b) Calculate the area of the triangular region enclosed by this tangent line and the coordinate axes.
2. **Find the inflection point:**
The inflection point occurs where the second derivative $f''(x)$ changes sign.
Calculate first derivative:
$$f'(x) = 3x^2 - 6x$$
Calculate second derivative:
$$f''(x) = 6x - 6$$
Set $f''(x) = 0$ to find inflection point:
$$6x - 6 = 0$$
$$6x = 6$$
$$x = 1$$
Find $y$ coordinate at $x=1$:
$$f(1) = 1^3 - 3(1)^2 + 3 = 1 - 3 + 3 = 1$$
So the inflection point is $W(1,1)$.
3. **Find the slope of the tangent at $W$:**
Evaluate $f'(1)$:
$$f'(1) = 3(1)^2 - 6(1) = 3 - 6 = -3$$
4. **Equation of the tangent line at $W$:**
Use point-slope form:
$$y - y_1 = m(x - x_1)$$
$$y - 1 = -3(x - 1)$$
$$y - 1 = -3x + 3$$
$$y = -3x + 4$$
5. **Find intercepts of the tangent line:**
- $y$-intercept: set $x=0$
$$y = -3(0) + 4 = 4$$
- $x$-intercept: set $y=0$
$$0 = -3x + 4$$
$$3x = 4$$
$$x = \frac{4}{3}$$
6. **Calculate the area of the triangle formed by the tangent and axes:**
The triangle has base on the $x$-axis from $0$ to $\frac{4}{3}$ and height on the $y$-axis from $0$ to $4$.
Area formula:
$$\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$$
Substitute values:
$$\text{Area} = \frac{1}{2} \times \frac{4}{3} \times 4 = \frac{1}{2} \times \frac{16}{3} = \frac{16}{6} = \frac{8}{3}$$
**Final answers:**
(a) Tangent line equation at inflection point: $$y = -3x + 4$$
(b) Area of the triangle enclosed by the tangent and coordinate axes: $$\frac{8}{3}$$
Tangent Inflection 319108
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