SOLUTION: The Slope of a line through the point (1,3) is 1.5. If the point (-3,y) lies on the line, find the value of y.

Algebra ->  Inequalities -> SOLUTION: The Slope of a line through the point (1,3) is 1.5. If the point (-3,y) lies on the line, find the value of y.       Log On


   

Question 35623: The Slope of a line through the point (1,3) is 1.5. If the point (-3,y) lies on the line, find the value of y.
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
+m+=+%28Rise%29%2F%28Run%29+

Also, a slope of 1.5 is actually one and a half or as a fraction it can be written m+=3%2F2.

The slope between (1,3) and (-3,y) is the RISE over the RUN, which is
m+=+%28y-3%29%2F%28-3-1%29

Therefore,
+%28y-3%29%2F%28-4%29+=+3%2F2

Since a%2Fb=c%2Fd means the same as ad=bc,
+%28y-3%29%2F%28-4%29+=+3%2F2 means that 2%28y-3%29+=+-4%2A3
2y-6+=+-12

Add +6 to each side:
2y+-6+%2B+6+=+-12+%2B+6
2y+=+-6
y=+-3

Check: Find the slope between (1,3) and (-3,-3).
m+=+%28-3-3%29%2F%28-3-1%29
m+=+%28-6%29%2F%28-4%29=+3%2F2=+1.5
It checks.

R^2 at SCC