Question 934263
if they vary directly, then k = y/x
if they very inversely, then k = y*x


this is because the equation for direct variation is y = k*x
solve for k and you get k = y/x


the equation for inverse variation is y = k/x
solve for k and you get k = y*x


k has to be the same for all of the pairs, not just some of them.


your first series is:


x = -2, 3, 8
y = -2.8, 4.2, 11.2 


we'll look for direct variation first.


-2.8 / -2 = 1.4
4.2 / 3 = 1.4
11.2 / 8 = 1.4


it's a direct variation equation.


your second series is:


x = 4, 5, 11
y = 3, 4.5, 13.5. 


we'll look for direct variation first.


3/4 = .75
4.5 / 5 = .9


it's not a direct variation.


let's look for inverse.


3 * 4 = 12
4.5 * 5 = 22.5


it's not an inverse variation.


this one is neither.