Question

When x = 2, y = 50 and when x = 4, y = 100. Which direct variation equation can be used to model this function?

xy = 100
xy = 400
y = 25x
y = 100x

Answer 1

y = 25x

Because k = y/x = 50/2 = 25, so the direct variation is y = 25x (and 25·4 = 100).