Then f (x1)-f (x2) = (x1-x2) (1-kloc-0/x1x2) is called a for convenience.

When x 1, x2∈(0, 1), a

When x 1, x2∈ 1, +∞, a >: 0, that is, f(x) increases monotonically.

2。 Because the function is monotonous,

Therefore, when x∈(0, 1), the range of f(x) is (f(x)min, f(x)max).

Namely: (f (1), f (1/4));

Similarly, when x∈ 1 and +∞, the range of f(x) is f (1) and f (2).