Identify the non permissible vaules
1 / 2(a-2b)
The non-permissible values are the values of a and b that make the denominator equal to zero.
In this case, the non-permissible values are when (a-2b) = 0. We can solve for this by setting it equal to zero and solving for a:
a - 2b = 0
a = 2b
So, the non-permissible values occur when a is equal to 2 times b.