# Thread: 5i for any integer i?.. Huh?

1. ## 5i for any integer i?.. Huh?

I am studying set theory at uni coming from a background of no formal maths education. I am understanding the basics because it is just like doing running SQL against a database. It is the assumed knowledge that is my undoing.

This is where I am currently getting stuck:
A={n ∈ Z|m=5i-1, for some integer i}
The bit that gets me is "m=5i-1". What do I do with the integer i?

Does it mean I add i to 5 then take 1? Or do I make 5 to the power of i? Or do I multiply 5 by i?

I am lost. Much thanks to anyone who can point me in the right direction.

2. Originally Posted by nasanu
This is where I am currently getting stuck:
A={n ∈ Z|m=5i-1, for some integer i}
The bit that gets me is "m=5i-1". What do I do with the integer i?
Does it mean I add i to 5 then take 1? Or do I make 5 to the power of i? Or do I multiply 5 by i?
You multiply 5 by i then subtract 1.

3. Thank you

I cant believe I've wasted so much time on something that simple