Please help me with this

Answer: [tex]a_{n}=4n+-3[/tex]
Step-by-step explanation:
The way arithmetic sequences are usually written is:
[tex]a_{n} =a_{1} +(n-1)d[/tex]
[tex]a_{n}[/tex] is the the term you are looking for. It has an n because we aren't looking for a specific one.
[tex]a_{1}[/tex] is the first term of the sequence. In this case that is 1.
n is the term position. Meaning if you wanted to find the fifth term you'd sub 5 in for n.
d is the common difference. In this case it is 4.
Now we can sub these values in.
[tex]a_{n} =1 +(n-1)4[/tex]
We can simplify the right part of the equation.
[tex]a_{n} =1 +(n-1)4\\a_{n} =1 +(4)(n)-(4)(1)\\a_{n}=1+4n-4\\a_{n}=4n+1-4\\a_{n}=4n+-3[/tex]