How to do this problem?

Programming with a computer? I'm not sure.

Let's talk about "the radical number in the big radical number set and the radical number in the small radical number set ...".

First of all, this is a real real number.

Because there are infinite radicals, one more radical and one less radical are still the same (infinite), and the value has not changed.

Maybe you didn't understand the above sentence. You can see it at the bottom.

Solution: Let this positive number = Y. Square both sides at the same time, and you get

y？ = 12- This "radical number set in large radical number set and small radical number set ...",

That is to say, or, appeared:

y？ =12-Y. (Haha, can you understand what I wrote here? )

y？ +y- 12=0。

∴ y = 3 or y =-4 (truncation).

A: This value is equal to 3.