Write the first three terms of the $APs$ when $a$ and $d$ are as given below:
$a = \frac{1}{2}, d = -\frac{1}{6}$

Given that,the first term $(a) = \frac{1}{2}$ and the common difference $(d) = -\frac{1}{6}$.
The general form of an $AP$ is $a, a+d, a+2d, \dots$
First term $(T_1) = a = \frac{1}{2}$.
Second term $(T_2) = a + d = \frac{1}{2} + (-\frac{1}{6}) = \frac{3}{6} - \frac{1}{6} = \frac{2}{6} = \frac{1}{3}$.
Third term $(T_3) = a + 2d = \frac{1}{2} + 2(-\frac{1}{6}) = \frac{1}{2} - \frac{1}{3} = \frac{3}{6} - \frac{2}{6} = \frac{1}{6}$.
Hence,the required three terms are $\frac{1}{2}, \frac{1}{3}, \frac{1}{6}$.