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Line segment [tex]$PR$[/tex] is a directed line segment beginning at [tex]$P(-10,7)$[/tex] and ending at [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 [tex]$4:5$[/tex].

A. [tex]$\left(0,-\frac{1}{3}\right)$[/tex]

B. [tex]$\left(-2,-\frac{5}{3}\right)$[/tex]

C. [tex]$\left(-2, \frac{5}{3}\right)$[/tex]

D. [tex]$\left(-\frac{9}{2}, 3\right)$[/tex]


Sagot :

To find the point [tex]\( Q \)[/tex] on the line segment [tex]\( PR \)[/tex] that partitions it into segments [tex]\( PQ \)[/tex] and [tex]\( QR \)[/tex] in the ratio [tex]\( 4:5 \)[/tex], we use the section formula. Given points [tex]\( P(-10, 7) \)[/tex] and [tex]\( R(8, -5) \)[/tex], and the ratios [tex]\( m=4 \)[/tex] and [tex]\( n=5 \)[/tex], the section formula in two dimensions helps us determine the coordinates of [tex]\( Q \)[/tex]. The formula for the coordinates [tex]\((Q_x, Q_y)\)[/tex] is given by:

[tex]\[ Q_x = \frac{m \cdot R_x + n \cdot P_x}{m + n} \][/tex]
[tex]\[ Q_y = \frac{m \cdot R_y + n \cdot P_y}{m + n} \][/tex]

Substituting the given values:

1. Calculate [tex]\( Q_x \)[/tex]:

[tex]\[ Q_x = \frac{4 \cdot 8 + 5 \cdot (-10)}{4 + 5} \][/tex]
[tex]\[ = \frac{32 - 50}{9} \][/tex]
[tex]\[ = \frac{-18}{9} \][/tex]
[tex]\[ = -2 \][/tex]

2. Calculate [tex]\( Q_y \)[/tex]:

[tex]\[ Q_y = \frac{4 \cdot (-5) + 5 \cdot 7}{4 + 5} \][/tex]
[tex]\[ = \frac{-20 + 35}{9} \][/tex]
[tex]\[ = \frac{15}{9} \][/tex]
[tex]\[ = \frac{5}{3} \][/tex]

Thus, the coordinates of the point [tex]\( Q \)[/tex] are:

[tex]\[ Q = \left(-2, \frac{5}{3}\right) \][/tex]

Therefore, the correct option is:
C. [tex]\(\left(-2, \frac{5}{3}\right)\)[/tex]