i am having trouble with my algebra homework and trying to work out if it is
right.Here's my question: 
X 1,2,3,4,5
Y 5,8,11,14,17
use the table above to write the rule that tells you how many of y you can get
for any number of x's. 
The way i worked it out is by finding out the first difference which is 3 so
then i said add 2 to make it 5 so this was my answer: 3x+2
I was wondering if i was correct and if i was wrong could you please tell me a
way to work it out.

For x = 1, we add 0 3's to the 5 to get the 1st term 5.
For x = 2, we add 1 3   to the 5 to get the 2nd term 8.
For x = 3, we add 2 3's to the 5 to get the 3rd term 11.
For x = 4, we add 3 3's to the 5 to get the 4th term 14.
For x = 5, we add 4 3's to the 5 to get the 5th term 17.

Following the pattern:

xth term = (x-1) times 3 added to the 5
xth term = 5 + 3(x-1) 
xth term = 5 + 3x - 3
xth term = 2 + 3x

Yeah, you're right.

Edwin