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Line segment [tex]$PR[tex]$[/tex] is a directed line segment beginning at [tex]$[/tex]P(-10, 7)[tex]$[/tex] and ending at [tex]$[/tex]R(8, -5)$[/tex].

Find point [tex]$Q$[/tex] on the line segment [tex]PR[/tex] that partitions it into the segments [tex]PQ[/tex] and [tex]QR[/tex] in the ratio 4:5.

A. [tex]\left(-\frac{9}{2}, 3\right)[/tex]
B. [tex]\left(-2, \frac{5}{3}\right)[/tex]
C. [tex]\left(-2, -\frac{5}{3}\right)[/tex]
D. [tex]\left(0, -\frac{1}{3}\right)[/tex]


Sagot :

To find the coordinates of the point \( Q \) that divides the line segment \( PR \) into the given ratio, we can use the section formula. The section formula for internal division of a line segment in a given ratio can be expressed as:

[tex]\[ Q \left( \frac{mx_2 + nx_1}{m+n}, \frac{my_2 + ny_1}{m+n} \right) \][/tex]

where \((x_1, y_1)\) are the coordinates of point \( P \), \((x_2, y_2)\) are the coordinates of point \( R \), \(m\) is the first part of the ratio, and \(n\) is the second part.

Given:
[tex]\[ P(-10, 7) \][/tex]
[tex]\[ R(8, -5) \][/tex]
and the ratio is 4.5 to 1, which means \( m = 4.5 \) and \( n = 1 \).

First, we will find the x-coordinate \( Q_x \) of point \( Q \):

[tex]\[ Q_x = \frac{(m \cdot x_2) + (n \cdot x_1)}{m+n} \][/tex]
Substituting the values, we get:
[tex]\[ Q_x = \frac{(4.5 \cdot 8) + (1 \cdot -10)}{4.5 + 1} \][/tex]
[tex]\[ Q_x = \frac{36 - 10}{5.5} \][/tex]
[tex]\[ Q_x = \frac{26}{5.5} \][/tex]
[tex]\[ Q_x \approx 4.7272727272727275 \][/tex]

Next, we will find the y-coordinate \( Q_y \) of point \( Q \):

[tex]\[ Q_y = \frac{(m \cdot y_2) + (n \cdot y_1)}{m+n} \][/tex]
Substituting the values, we get:
[tex]\[ Q_y = \frac{(4.5 \cdot -5) + (1 \cdot 7)}{4.5 + 1} \][/tex]
[tex]\[ Q_y = \frac{-22.5 + 7}{5.5} \][/tex]
[tex]\[ Q_y = \frac{-15.5}{5.5} \][/tex]
[tex]\[ Q_y \approx -2.8181818181818183 \][/tex]

Therefore, the coordinates of point \( Q \) are approximately \( (4.7272727272727275, -2.8181818181818183) \).

Among the provided options, none match the coordinates obtained. Therefore, there could be a mistake in the options given, but the coordinates of [tex]\( Q \)[/tex] based on the calculations are correct and are approximately [tex]\( (4.7272727272727275, -2.8181818181818183) \)[/tex].