Find a so that the points (–3,1) (5,–2) and (a,10) are collinear. (Coordinate geomtry)

Question

"Find a so that the points (–3,1) (5,–2) and (a,10) are collinear"

 

 

 

Answer 1

First, let's find the slope of the line through (-3,1), (5,-2)

 

The slope is (change in y)/(change in x):

m= (-2-1)/(5-(-3)) = -3/8

 

We now need the value of "a" that gives the same

slope between (a,10) and one of the original points.

Let's use (5,-2)

 

-3/8 = (10-(-2))/(a-5)

-3/8 = 12/(a-5)

Cross multiply

8(12) = -3(a-5)

96 = -3a + 15

81 = -3a

-27 = a

 

your collinear point is (-27,10)