Consider the directed line segment [tex]PQ[/tex]. Point [tex]P[/tex] is located at [tex](-10, 3)[/tex]. Point [tex]R[/tex], which is on segment [tex]PQ[/tex] and divides segment [tex]PQ[/tex] into a ratio of [tex]PR : RQ = 2 : 3[/tex], is located at [tex](4, 7)[/tex].

What are the coordinates of point [tex]Q[/tex]?

A. [tex]\left(-\frac{2\pi}{5}, \frac{23}{5}\right)[/tex]
B. [tex](25, 13)[/tex]
C. [tex](-5, 13)[/tex]
D. [tex](25, 22)[/tex]



Answer :

To find the coordinates of point [tex]\( Q \)[/tex], we can use the section formula, which helps determine the coordinates of a point that divides a line segment internally in a given ratio. Given:

- Point [tex]\( P \)[/tex] at [tex]\( (-10, 3) \)[/tex]
- Point [tex]\( R \)[/tex] at [tex]\( (4, 7) \)[/tex]
- Ratio [tex]\( PR : RQ = 2 : 3 \)[/tex]

Let's denote the coordinates of point [tex]\( Q \)[/tex] as [tex]\( (x, y) \)[/tex].

The section formula for a point [tex]\( R \)[/tex] that divides a line segment [tex]\( PQ \)[/tex] internally in the ratio [tex]\( m : n \)[/tex] is given by:

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

Since point [tex]\( R \)[/tex] divides the segment [tex]\( PQ \)[/tex] in the ratio [tex]\( 2 : 3 \)[/tex]:

[tex]\[ (4, 7) = \left( \frac{2x + 3(-10)}{2+3}, \frac{2y + 3(3)}{2+3} \right) \][/tex]

Simplifying the x-coordinate:

[tex]\[ 4 = \frac{2x + 3(-10)}{5} \][/tex]

Multiplying both sides by 5:

[tex]\[ 20 = 2x + 3(-10) \][/tex]

[tex]\[ 20 = 2x - 30 \][/tex]

Adding 30 to both sides:

[tex]\[ 50 = 2x \][/tex]

Dividing by 2:

[tex]\[ x = 25 \][/tex]

Now for the y-coordinate:

[tex]\[ 7 = \frac{2y + 3(3)}{5} \][/tex]

[tex]\[ 7 = \frac{2y + 9}{5} \][/tex]

Multiplying both sides by 5:

[tex]\[ 35 = 2y + 9 \][/tex]

Subtracting 9 from both sides:

[tex]\[ 26 = 2y \][/tex]

Dividing by 2:

[tex]\[ y = 13 \][/tex]

Therefore, the coordinates of point [tex]\( Q \)[/tex] are [tex]\( (25, 13) \)[/tex].

So, the correct answer is:

B. [tex]\( (25, 13) \)[/tex]