let
v=-u
dv=-du
u=0, v=0
u=-x, v=x
F(x) =∫(0->x) f(u) du
F(-x)
=∫(0->-x) f(u) du
=∫(0->x) f(-v) (-dv)
f(-v)=-f(v)
=∫(0->x) [-f(v) ] (-dv)
=∫(0->x) f(v) dv
