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.