SOLUTION: find the value of x so that the line joining the points (x,3) and (2,1) is parallel to the line joining (x,5) and (-1,2).

Algebra ->  Linear-equations -> SOLUTION: find the value of x so that the line joining the points (x,3) and (2,1) is parallel to the line joining (x,5) and (-1,2).      Log On


   

Question 607221: find the value of x so that the line joining the points (x,3) and (2,1) is parallel to the line joining (x,5) and (-1,2).
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
find the value of x so that the line joining the points (x,3) and (2,1) is parallel to the line joining (x,5) and (-1,2).
:
The slope formula: m = %28y2-y1%29%2F%28x2-x1%29
parallel lines have equal slopes therefore we can write an equation;
Slope 1 = slope 1
%281-3%29%2F%282-x%29 = %282-5%29%2F%28-1-x%29
:
%28-2%29%2F%282-x%29 = %28-3%29%2F%28-1-x%29
Cross multiply
-2(-1-x) = -3(2-x)
2 + 2x = -6 + 3x
2 + 6 = 3x = 2x
8 = x
:
:
Check this by finding the slopes when x=8
%281-3%29%2F%282-8%29 = %282-5%29%2F%28-1-8%29
%28-2%29%2F%28-6%29 = %28-3%29%2F%28-9%29
2%2F6 = 3%2F9; both reduce to 1/3