a)

căn(5-2 căn 6)^2 - căn(5+2 căn 6)^2

First, let's simplify the expressions inside the square roots:

5-2 căn 6 = 5-2√6
5+2 căn 6 = 5+2√6

Now, let's square these expressions:

(5-2√6)^2 = (5-2√6)(5-2√6) = 25 - 10√6 + 24 = 49 - 10√6
(5+2√6)^2 = (5+2√6)(5+2√6) = 25 + 10√6 + 24 = 49 + 10√6

Now, let's take the square root of these squared expressions:

căn(49 - 10√6) - căn(49 + 10√6)

b)

căn(3-2 căn 2)^2 - căn(3+2 căn 2)^2

First, let's simplify the expressions inside the square roots:

3-2 căn 2
3+2 căn 2

Now, let's square these expressions:

(3-2√2)^2 = (3-2√2)(3-2√2) = 9 - 6√2 + 8 = 17 - 6√2
(3+2√2)^2 = (3+2√2)(3+2√2) = 9 + 6√2 + 8 = 17 + 6√2

Now, let's take the square root of these squared expressions:

căn(17 - 6√2) - căn(17 + 6√2)