You have the following sequence given in the exercise:
[tex]\frac{1}{4},\frac{2}{4},\frac{3}{4},\frac{4}{4},\ldots[/tex]You can identify that it is an Arithmetic sequence, because the difference between one term and the previous one is always the same:
[tex]\begin{gathered} \frac{2}{4}-\frac{1}{4}=\frac{1}{4} \\ \\ \frac{3}{4}-\frac{2}{4}=\frac{1}{4} \\ \\ \frac{4}{4}-\frac{3}{4}=\frac{1}{4} \end{gathered}[/tex]By definition, you can express an Arithmetic sequence using a rule:
[tex]a_n=a_1+d(n-1)_{}[/tex]Where:
- The nth term of the sequence is
[tex]a_n[/tex]- The first term is
[tex]a_1[/tex]- The common difference is "d".
- The term position is "n".
In this case you know that:
[tex]\begin{gathered} d=\frac{1}{4} \\ \\ a_1=\frac{1}{4} \end{gathered}[/tex]Therefore, you can substitute this value into
[tex]a_n=a_1+d(n-1)_{}[/tex]Then, you get that the answer is:
[tex]a_n=\frac{1}{4}+\frac{1}{4}(n-1)[/tex]