I've been pondering this question as to how and when you can perform an operation on a complete "unit" and the answer is the same when performing the operation on the individual parts of the "unit"
For example:
$$ \sqrt{25\div4} = \sqrt{25}\div\sqrt{4}. $$ We took the square root operation and applied it to $25$ and $4$ separately to get the same result.
However this is not the case for:
$$ (4+1)^2 \neq 4^2 + 1^2 $$
However this is true again for:
$$ \frac{2(7-6)}{2^2} = \frac{2(7)}{2^2} - \frac{2(6)}{2^2}. $$
We took multiplication by $2$ and division by $2^2$ and applied them to $7$ and $6$ individually.
My question is: Can you always distribute operations to the parts of a unit and get the same result as when you would perform the operation on the whole unit.