A line segment is bisected by a line with the equation 3 y - 7 x = 2 . If one end of the line segment is at (7 ,8 ), where is the other end?

1 Answer
Oct 28, 2016

The other end is at the point: (14/29, 313/29)

Explanation:

Rewrite the given line in slope-intercept form so that we can obtain the slope, m, of the line.

y = 7/3x + 2/3 color(white)_[1]

We observe that m = 7/3

The slope, n, of the bisected line is the negative reciprocal of m:

n = -1/m

n = -3/7

Use this slope and the given point to solve for b in the slope-intercept form, y = nx + b:

8 = -3/7(7) + b

b = 11

The equation of the bisected line is:

y = -3/7x + 11 color(white)_[2]

Subtract equation [2] from equation [1]:

y- y = 7/3x + 3/7x + 2/3 - 11

0 = 58/21x - 31/3

58/21x = 31/3

The x coordinate of the point two lines intersect is: x = 217/58

The change in x from the point (7,8) to the point of intersection is:

Deltax = 217/58 - 7

Deltax = -189/58

To go to the other end of the line we must move twice that far in same direction:

2Deltax = -378/58

The add 7 to find the x coordinate of the other end of the line segment:

7 + 2Deltax = 7 -378/58 = 28/58 = 14/29

To find the y coordinate of the other end of the line segment substitute 14/28 for x in equation [2]:

y = -3/7(14/29) + 11

y = 313/29