Let x = length. Therefore , `[ X] = [L]` and `[ dx] = [L]`.
By the principle of dimensional homogenity, `[(x)/(a)]` = dimensionless.
:. `[a] = [x] = [L]`
By substituting the dimension of each quantity in both sides,
`([L])/([L^(2) - L^(2)]^(1//2)) = [L^(n)] rArr n = 0`