Given that f (x) is an odd function and a decreasing function on (- ∞, + ∞), and X1 + x2 > 0, & nbsp; & amp; X1 + X3 > 0, X2 + X3 > 0, then the relation between F (x1) + F (x2) + F (X3) and 0 is zero______ .

Given that f (x) is an odd function and a decreasing function on (- ∞, + ∞), and X1 + x2 > 0, & nbsp; & amp; X1 + X3 > 0, X2 + X3 > 0, then the relation between F (x1) + F (x2) + F (X3) and 0 is zero______ .

∵ function f (x) is an odd function and a decreasing function on (- ∞, + ∞) ∵ X1 + x2 > 0, X2 + x3 > 0, X3 + x1 > 0, ∵ x1 > - X2, X2 > - x3x3x3 > - x1, ∵ f (x1) < f (- X2,) f (x2) < f (- x3), f (x3) < f (- x1) ∵ f (x1) + F (x2) < 0, f (x2) + F (X3