Which equation represents a line that is perpendicular to the line passing through [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex]?

A. [tex] y = \frac{5}{4}x + 8 [/tex]
B. [tex] y = -\frac{4}{5}x + 6 [/tex]
C. [tex] y = -\frac{5}{4}x - 2 [/tex]
D. [tex] y = \frac{4}{5}x - 3 [/tex]



Answer :

To determine which equation represents a line that is perpendicular to the line passing through the points [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex], we need to follow these steps:

1. Calculate the slope of the line passing through the given points:

The slope [tex]\(m\)[/tex] of a line passing through two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] can be found using the formula:

[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

Plugging in the coordinates [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex]:

[tex]\[ m = \frac{3 - 7}{1 - (-4)} = \frac{3 - 7}{1 + 4} = \frac{-4}{5} = -\frac{4}{5} \][/tex]

2. Determine the slope of the perpendicular line:

The slope of a line that is perpendicular to another line is the negative reciprocal of the slope of the original line. If the slope of the original line is [tex]\(m\)[/tex], the slope of the perpendicular line [tex]\(m_{\perpendicular}\)[/tex] is:

[tex]\[ m_{\perpendicular} = -\frac{1}{m} \][/tex]

Given the original slope [tex]\(m = -\frac{4}{5}\)[/tex], the slope of the perpendicular line is:

[tex]\[ m_{\perpendicular} = -\frac{1}{-\frac{4}{5}} = \frac{5}{4} \][/tex]

3. Match the perpendicular slope with the options provided:

We are looking for an equation with a slope of [tex]\(\frac{5}{4}\)[/tex]. Let's examine the slopes in each option:

- Option A: [tex]\(y = \frac{5}{4} x + 8\)[/tex] has a slope of [tex]\(\frac{5}{4}\)[/tex]
- Option B: [tex]\(y = -\frac{4}{5} x + 6\)[/tex] has a slope of [tex]\(-\frac{4}{5}\)[/tex]
- Option C: [tex]\(y = -\frac{5}{4} x - 2\)[/tex] has a slope of [tex]\(-\frac{5}{4}\)[/tex]
- Option D: [tex]\(y = \frac{4}{5} x - 3\)[/tex] has a slope of [tex]\(\frac{4}{5}\)[/tex]

The correct option that has a slope of [tex]\(\frac{5}{4}\)[/tex] is Option A.

Therefore, the equation that represents a line perpendicular to the line passing through [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex] is:
[tex]\[ \boxed{y = \frac{5}{4} x + 8} \][/tex]