SOLUTION: If the line passing through the points (a, 1) and (15, 6) is parallel to the line passing through the points (14, 7) and (a + 2, 1), what is the value of a?

Algebra.Com
Question 710243: If the line passing through the points
(a, 1) and (15, 6)
is parallel to the line passing through the points
(14, 7) and (a + 2, 1),
what is the value of a?
Found 2 solutions by solver91311, Edwin McCravy:
Answer by solver91311(24713)   (Show Source): You can put this solution on YOUR website!


Use the slope formula:



where and are the coordinates of the given points.

to calculate the slope of the first line in terms of . Then do the same thing for the other two points. Since parallel lines have equal slopes, set the two fractions equal to each other and then solve for

John

Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
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Answer by Edwin McCravy(20055)   (Show Source): You can put this solution on YOUR website!
Find the slope of the first line using the slope formula:

m = 

where (x1,y1) = (a,1)

and where (x2,y2) = (15,6)

m = 

m = 

Find the slope of the second line using the slope formula:

m = 

where (x1,y1) = (14,7)

and where (x2,y2) = (a+2,1)

m = 

m = 

m = 

Since they are parallel their slopes are equal, so we 
set the two slopes equal:

 = 

Cross multiply and solve and get a=30

Edwin
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