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



Answer :

Let's start by determining the slope of the line that passes through the points [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex].

The formula for 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] is given by:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

Substituting the coordinates of the given points:
[tex]\[ m = \frac{3 - 7}{1 - (-4)} = \frac{3 - 7}{1 + 4} = \frac{-4}{5} \][/tex]

So, the slope of the line passing through [tex]\((-4, 7)\)[/tex] and [tex]\((1, 3)\)[/tex] is [tex]\(\frac{-4}{5}\)[/tex].

Now, we want to find a line that is perpendicular to this line. The slope of a line perpendicular to a given line is the negative reciprocal of the slope of the given line.

The negative reciprocal of [tex]\(\frac{-4}{5}\)[/tex] is:
[tex]\[ -\frac{1}{\frac{-4}{5}} = 5/4 \][/tex]

Thus, the slope of the line that is perpendicular to the given line is [tex]\(\frac{5}{4}\)[/tex].

Next, let's check the slopes of the given equations to determine which one has a slope of [tex]\(\frac{5}{4}\)[/tex]:

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

From the above analysis, it is clear that Equation A has a slope of [tex]\(\frac{5}{4}\)[/tex], which matches the slope we found for the perpendicular line.

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]
which corresponds to choice A (Answer 1).