SOLUTION: A line has a slope of -4 and includes the points (r,6) and (-1,-10). What is the value of r? r= Thank you

Algebra ->  Linear-equations -> SOLUTION: A line has a slope of -4 and includes the points (r,6) and (-1,-10). What is the value of r? r= Thank you       Log On


   

Question 1088436: A line has a slope of -4 and includes the points (r,6) and (-1,-10). What is the value of r?
r=
Thank you
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Slope formula:
m+=+%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29


The two points are and .
The given slope is m+=+-4


Plug all of this info into the slope formula. Then isolate r.


m+=+%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29


-4+=+%28-10-6%29%2F%28-1-r%29


-4+=+%28-16%29%2F%28-1-r%29


-4%28-1-r%29+=+%28%28-16%29%2F%28-1-r%29%29%2A%28-1-r%29


-4%28-1-r%29+=+-16


4%2B4r+=+-16


4%2B4r-4+=+-16-4


4r+=+-20


%284r%29%2F%284%29+=+%28-20%29%2F%284%29


r+=+-5