Question

Determine whether y varies directly with x. if so, find the constant of variation k and write the equation.


x y
4 6.4
7 11.2
10 16
13 20.8

Answer 1

Assume y varies direct with x
then y = kx
testing with (10,16)
16 = 10k
k = 1.6

so your equation would be y = 1.6x
check if true for the other points

e.g. the last one ...
x = 13, y = 20.8
is 20.8 = 1.6(13) ? , YES
check if true for all points, if so,
then y varies directly with x and
y = 1.6x

Answer 2

from one site