To find the equation of the line passing through the points (7, –4) and (–1, 3), we first need to calculate the slope (m) using the formula:
\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]
Here, we can assign:
- Point 1: \((x_1, y_1) = (7, -4)\)
- Point 2: \((x_2, y_2) = (-1, 3)\)
Plugging in the coordinates:
\[ m = \frac{3 - (-4)}{-1 - 7} = \frac{3 + 4}{-1 - 7} = \frac{7}{-8} = -\frac{7}{8} \]
So, the slope of the line is \(-\frac{7}{8}\).
Point-Slope Form
The point-slope form of a line is given by the equation:
\[ y - y_1 = m(x - x_1) \]
Using the point (7, -4):
\[ y - (-4) = -\frac{7}{8}(x - 7) \]
This simplifies to:
\[ y + 4 = -\frac{7}{8}(x - 7) \]
So the point-slope form of the line is
\[ y + 4 = -\frac{7}{8}(x - 7) \]
Slope-Intercept Form
To convert to slope-intercept form (y = mx + b), we can distribute and isolate y. Starting from the point-slope form:
\[ y + 4 = -\frac{7}{8}(x - 7) \]
Distributing the slope:
\[ y + 4 = -\frac{7}{8}x + \frac{49}{8} \]
Now, subtract 4 from both sides. We convert 4 to a fraction with a denominator of 8:
\[ 4 = \frac{32}{8} \]
So we have:
\[ y = -\frac{7}{8}x + \frac{49}{8} - \frac{32}{8} \]
Combining the constant terms gives:
\[ y = -\frac{7}{8}x + \frac{17}{8} \]
Thus, the slope-intercept form of the line is
\[ y = -\frac{7}{8}x + \frac{17}{8} \]
Summary
- The slope of the line is \(-\frac{7}{8}\).
- The point-slope form of the line is \(y + 4 = -\frac{7}{8}(x - 7)\).
- The slope-intercept form of the line is \(y = -\frac{7}{8}x + \frac{17}{8}\).