SOLUTION: Hi! Given a sequence like this: when n=1, x=1 when n=2, x=5 when n=3, x=9 when n=4, x=13 ... and so on, how do you come up with an equation to represent that relationship? I k

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: Hi! Given a sequence like this: when n=1, x=1 when n=2, x=5 when n=3, x=9 when n=4, x=13 ... and so on, how do you come up with an equation to represent that relationship? I k      Log On


   



Question 217540: Hi! Given a sequence like this:
when n=1, x=1
when n=2, x=5
when n=3, x=9
when n=4, x=13
... and so on, how do you come up with an equation to represent that relationship? I know the answer is 4n-3=x because I looked it up in the back of the book. But how do you figure that out on your own?
Please help! thank you!
cherilyn

Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
the difference between two consecutive values of x is always 4 ___ 1 & 5, 5 & 9, 9 & 13

this makes the series arithmetic (as opposed to geometric) and 4 is the "constant difference"

so, 4n + ? = x ___ the ? is what I call the "fudge factor" ___ you can find it by just taking a pair of n and x values

4(2) + ? = 5 ___ 8 + ? = 5 ___ ? = -3