0372132人目の素数さん
2017/12/01(金) 22:53:39.42ID:jDGDIkRqs = a+b+c,t = ab+bc+ca,u = abc,
とおくと、
(左辺)={3u +2(tt-2su)+(ss-2t)u}/{u +(tt-2su)+(ss-2t)u + uu},
2(分子)-3(分母)= 3u +(tt-2su)-(ss-2t)u -3uu
=(t^3 -4stu +9uu)/t + (tt-3su)u/t +(st-9u)u/3 (s=3)
≧ 0,
t^3 -4stu +9uu = uuF_{-2}(a,b,c)≧ 0,
tt -3su = uF_{-1}(a,b,c)≧ 0,
st -9u = a(b-c)^2 + b(c-a)^2 + c(a-b)^2 ≧ 0,