SOLUTION: if the line passing through the points (2,a) and (5,-3) is parallel to the line passing through the points (4,8) and (-5,a+1), what is the value of a?

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: if the line passing through the points (2,a) and (5,-3) is parallel to the line passing through the points (4,8) and (-5,a+1), what is the value of a?      Log On


   



Question 964541: if the line passing through the points (2,a) and (5,-3) is parallel to the line passing through the points (4,8) and (-5,a+1), what is the value of a?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Parallel lines have identical slopes.
Find the slope for each line.
m%5B1%5D=%28-3-a%29%2F%285-2%29=-%28a%2B3%29%2F3
m%5B2%5D=%28a%2B1-8%29%2F%28-5-4%29=+-%28a-7%29%2F%289%29+
.
.
m%5B1%5D=m%5B2%5D
-%28a%2B3%29%2F3=-%28a-7%29%2F%289%29
9%28a%2B3%29=3%28a-7%29
9a%2B27=3a-21
6a=-48
a=-8