1. **State the problem:** Find the slope of the tangent line to the graph of $f(x) = 3x^2 - 12x + 14$ at the point $(1,5)$ and then find the equation of the tangent line in the form $y = mx + b$.
2. **Formula for slope of tangent line:** The slope $m$ at $x=1$ is given by the derivative of $f(x)$ at $x=1$, which can be found using the limit definition:
$$m = \lim_{h \to 0} \frac{f(1+h) - f(1)}{h}$$
3. **Calculate $f(1)$:**
$$f(1) = 3(1)^2 - 12(1) + 14 = 3 - 12 + 14 = 5$$
4. **Calculate $f(1+h)$:**
$$f(1+h) = 3(1+h)^2 - 12(1+h) + 14 = 3(1 + 2h + h^2) - 12 - 12h + 14 = 3 + 6h + 3h^2 - 12 - 12h + 14$$
Simplify:
$$= (3 - 12 + 14) + (6h - 12h) + 3h^2 = 5 - 6h + 3h^2$$
5. **Form the difference quotient:**
$$\frac{f(1+h) - f(1)}{h} = \frac{(5 - 6h + 3h^2) - 5}{h} = \frac{-6h + 3h^2}{h}$$
6. **Simplify the fraction by canceling $h$:**
$$\frac{\cancel{h}(-6 + 3h)}{\cancel{h}} = -6 + 3h$$
7. **Take the limit as $h \to 0$:**
$$m = \lim_{h \to 0} (-6 + 3h) = -6 + 3(0) = -6$$
8. **Find the equation of the tangent line:**
We know the slope $m = -6$ and the point $(1,5)$ lies on the line.
Use point-slope form:
$$y - y_1 = m(x - x_1)$$
$$y - 5 = -6(x - 1)$$
9. **Simplify to slope-intercept form $y = mx + b$:**
$$y - 5 = -6x + 6$$
$$y = -6x + 6 + 5$$
$$y = -6x + 11$$
10. **Identify $m$ and $b$:**
$$m = -6$$
$$b = 11$$
**Final answer:**
The slope of the tangent line at $(1,5)$ is $-6$.
The equation of the tangent line is $$y = -6x + 11$$.
Tangent Line Eba942
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