LOOK AT THE EQUATION !
The equation tells everything that Y depends on, and what the exact value of Y is for every possible value of all the things that it depends on.
THIS equation says: "The value of Y depends on '2'. At every moment, no matter what the value of '2' is, Y is equal to it."
The equation tells you that.
So now, we can actually tell the future ! We know that the value of '2' is always going to be TWO. If we use the powerful equation that we have, we know that Y is always going to be TWO.
Does the value of Y depend on the value of X ? If it does, then X must be there on the right side of the equation. But X is not there ! That means that X has no influence on the value of Y. Y is always 2 !
You say X=5 ? That's nice. Who cares ? ! ? It has no influence on Y . Y is ALWAYS 2 .
