How do you tell wether the equation y = 2x + 1 represents direct variation and if so, how do you identify the constant of variation?

1 Answer
Dec 15, 2017

y=2x+1 is not direct variation.

Explanation:

2 variables which are directly proportional can be written in the form

y=kx

for some constant k. This means that if either x or y is doubled, the other is doubled as well.

Since y=2x+1 does not pass through the origin (i.e. there exists the constant term of 1), the variables y and x are not directly proportional - though, they do have a linear relationship.