X=2
I have an image showing all work
Given:
3,6,9,12,15,18...
We need to find the difference.
The difference between 3 and 6 is 6-3 =3.
The difference between 6 and 9 is 9-6 =3.
The difference between 9 and 12 is 12-9 =3.
The difference between 12 and 15 is 15-12 =3.
The difference between 15 and 18 is 18-15 =3.
Recall that linear have equal differences.
We get an equal difference between each value.
The form of the equation is

Hence the given is linear.
Image of graph The domain of the expression is all real numbers except where the expression is undefined. In this case, there is no real number that makes the expression undefined.
Answer: the first one
Step-by-step explanation: