How do you write the expression for the nth term of the sequence given 2/1, 3/3, 4/5, 5/7, 6/9,...?

If we take $\frac{2}{1}$ as the first term, and see that the numerators differ $1$ and the denominators differ $2$.
${t}_{n} = \frac{1 + 1 \times n}{1 + 2 \times \left(n - 1\right)} = \frac{n + 1}{2 n - 1}$