SOLUTION: A line passing through (-4,4) and (x,-8) is perpendicular to a line with slope 5/12. Find the value of x.

Algebra ->  Linear-equations -> SOLUTION: A line passing through (-4,4) and (x,-8) is perpendicular to a line with slope 5/12. Find the value of x.      Log On


   

Question 139826: A line passing through (-4,4) and (x,-8) is perpendicular to a line with slope 5/12. Find the value of x.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A line passing through (-4,4) and (x,-8) is perpendicular to a line with slope 5/12. Find the value of x.
:
m1 = slope of the given coordinates
m2 = 5/12
;
We know that the relationship of the slopes of perpendicular lines is:
m1 * m2 = -1
m1 *5%2F12 = -1
Multiply equation by 12:
m1 * 5 = -12
m1 = -12%2F5
:
Using the slope formula; (y2-y1)/(x2-x1) = m:
%28-8+-+4%29%2F%28x+-%28-4%29%29 = -12%2F5
:
You can see that x has to = 1, but here is the algebra to solve it:
%28-12%29%2F%28%28x%2B4%29%29 = -12%2F5
neg on both sides:
12%2F%28%28x%2B4%29%29 = 12%2F5
cross multiply, solve for x:
12(x+4) = 12 * 5
12x + 48 = 60
12x = 60 - 48
12x = 12
x = 1