It is known that the function y = f (x) is an odd function on R and an increasing function on (0, + ∞). It is proved that: (1) f (0) = 0; (2) y = f (x) is also an increasing function on (- ∞, 0)

It is known that the function y = f (x) is an odd function on R and an increasing function on (0, + ∞). It is proved that: (1) f (0) = 0; (2) y = f (x) is also an increasing function on (- ∞, 0)

It is proved that: (1) f (x) & nbsp; If x 1 < x 2 < 0, then - x 1 > - x 2 > 0, ∵ f (x) is an increasing function on (0, + ∞), f (- x 1) > f (- x 2), and f (x) is an odd function on R, then - f (x 1) > - f (x 2), that is, f (x 1) < f (x 2) and y = f (x) are increasing functions on (- ∞, 0) Count