Find the Third Term t_n=2n^2-n

$t_{n} = 2 n^{2} - n$

Substitute in the value of $n$ to find the $n$ th term.

$t_{3} = 2 {(3)}^{2} - (3)$

Simplify each term.

Raise $3$ to the power of $2$ .

$t_{3} = 2 \cdot 9 - (3)$

Multiply $2$ by $9$ .

$t_{3} = 18 - (3)$

Multiply $- 1$ by $3$ .

$t_{3} = 18 - 3$

Subtract $3$ from $18$ .

$t_{3} = 15$