Question

A direct variation goes through the points (1, 4) and (2, 8). What is the constant of variation?

Answer 1

The constant of variation is the slope defined by those points.

Answer 2

the slope of 2 points
(x1,y1) , (x2,y2)
slope = (y2-y1)/(x2-x1)

Answer 3

you don't need two points
divide the second coordinate by the first in either pair, that is all

Answer 4

i.e either \(4\div1\) or \(8\div2\)

Answer 5

you used the origin . still 2 points ..