Question:

While solving for velocity in a kinematics problem, you derive the following equation.

$v_i=\frac{x_f-x_i}{t}-\sqrt[\phantom{2}]{\frac{at}{2}}$

The variables stand for the following quantities.

$v_i$ : velocity

$x_f$ : final position

$x_i$ : initial position

$a$ : acceleration

t: time

Based on a units check, which term$($s$)$ in this equation has INCORRECT units?