Make the absolute value of f(x 1)-g(x2) less than 1,

That is to say, it is only necessary that the minimum value of the absolute value of f(x 1)-g(x2) on (0,4) is less than 1.

From the first question, f(x) increases in (0,3) and decreases in (3,4).

And g(x) increases at (0,4).

Therefore, the minimum value of the absolute value of f(x 1)-g(x2) is taken as f(3)-g(0).

If the topic is about any x 1, x2 belongs to (0,4), so the absolute value of f(x 1)-g(x2) is less than 1.

Then think about it like you do.