A line segment is bisected by a line with the equation 2 y + 3 x = 3 . If one end of the line segment is at ( 1 , 8 ), where is the other end?

1 Answer
Dec 18, 2016

To other end is at the point (-83/13,40/13)

Explanation:

The equation of any line segment that has the line,

3x + 2y = 3" [1]"

, as its perpendicular bisector will have the standard form:

2x - 3y = C

To find the value of C for the specified line segment, substitute the point (1, 8) into the equation:

2(1) - 3(8) = C

And then solve for C:

C = -22

The equation of the bisected line segment is:

2x - 3y = -22" [2]"

We shall use equations [1] and [2] to find the x coordinate of the point of intersection, x_i.

Multiply equation [1] by 3 and equation [2] by 2:

9x_i + 6y_i = 9" [3]"
4x_i - 6y_i = -44" [4]"

Add equation [3] to equation [4]:

13x_i = -35

x_i = -35/13

The change in x (Deltax) from the starting point to the point of intersection is as follows:

Deltax = (-35/13 - 1)

Deltax = -48/13

The x coordinate of the other end, x_e can be computed as follows:

x_e = 2Deltax + x_s

where x_s is the starting x coordinate, x_s = 1:

x_e = 2(-48/13) + 1

x_e = -83/13

To find the corresponding y coordinate, y_e substitute x_e into equation [2]:

2(-83/13) - 3y_e = -22

y_e = 40/13

To other end is at the point (-83/13,40/13)

Here is a graph with the two lines and the start and end points plotted:

![Desmos.com](useruploads.socratic.org)