x^4-15x^2-27
=x^4-15x^2+(15/2)^2-(15/2)^2-27
=(x^2-15/2)^2-[3/2*sqrt(37)]^2
=[x^2-15/2-3/2*sqrt(37)][x^2-15/2+3/2*sqrt(37)]
=(x-sqrt((15+3sqrt(37))/2))(x+sqrt((15+3sqrt(37))/2))(x^2+(3sqrt(37)-15)/2))

【 在 oolliivveerr 的大作中提到: 】
: [upload=1][/upload]
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