The points (a,1), (9,0), and (-3,4) lie on a straight line. Find a.
The slope between points on a line will be constant
So
(4 - 0) /( -3-9) = 4 / (-12) = -1/3 = slope
(0 - 1) / (9 - a) = -1 / 3
- 1 / ( 9 -a) = -1/3
This implies that 9 - a = 3
So a = 6
