Question: Find the equation of a trend line using
$(-2, 8)$ and $(1, -1)$ as anchor points.
y = [?]x + [ ]
1. **State the problem:** Find the equation of the line passing through points $(-2, 8)$ and $(1, -1)$.
2. **Formula used:** The slope $m$ of a line through points $(x_1, y_1)$ and $(x_2, y_2)$ is given by:
$$m = \frac{y_2 - y_1}{x_2 - x_1}$$
3. **Calculate the slope:**
$$m = \frac{-1 - 8}{1 - (-2)} = \frac{-9}{1 + 2} = \frac{-9}{3} = -3$$
4. **Use point-slope form:**
$$y - y_1 = m(x - x_1)$$
Using point $(-2, 8)$:
$$y - 8 = -3(x - (-2))$$
$$y - 8 = -3(x + 2)$$
5. **Simplify:**
$$y - 8 = -3x - 6$$
$$y = -3x - 6 + 8$$
$$y = -3x + 2$$
6. **Final answer:** The equation of the trend line is:
$$y = -3x + 2$$