0350132人目の素数さん
2018/11/19(月) 00:15:59.14ID:eL1RQppsf(x) = (x^2+2ax+b) (x^2+2cx+d)
とする。
x^2 +2ax +b = X^2 +2√(7/6 +f/2)・(X-g) +f,
判別式 a^2 -b = (7/6 +f/2) -f +2g√(7/6 +f/2)
= (7/6 -f/2) +20/[27√(7/6 +f/2)]
= 0.5274900867207
x^2 +2cx +d = X^2 -2√(7/6 +f/2)・(X-g) +f,
判別式 c^2 -d = (7/6 +f/2) -f -2g√(7/6 +f/2)
= (7/6 -f/2) -20/[27√(7/6 +f/2)]
= -0.4504709612713
(a^2 -b)(c^2 -d) = (7/6 -f/2)^2 -(80/27)^2/(7/6 +f/2)
= -(4/3)[10 - (13+2√11)^{2/3} - (13-2√11)^{2/3}]
= -0.237618966426144
< 0,