[代數] irreducible

[ss1132 (景)]

Prove that
 f(x,y)=xy^3+x^2y^2-x^5y+x^2+1
is an irreducible polynomial in /R[x,y]

我的想法是令Q=/R(x)
證f(x,y)屬於Q[y]沒有根
三次式沒有根就是irreducible

然後就卡住了
麻煩大家謝謝

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