A direct variation function contains the points (2, 14) and (4, 28). Which equation represents the function?
28-14
Find the slope, m: m = ------------ = 14/2 = 7
4-2
Now find the equation of this line by using the point-slope equation:
y-28 = (7)(x-4)
You could change this to point-slope form: y = 28 + 7(x-4), or y = 7x