题目已知:A=x2−1A=x^{2}-1A=x2−1,B=x2y3−xy3B=x^{2}y^{3}-xy^{3}B=x2y3−xy3,C=(x+1)(x−3)+4C=\left(x+1\right)\left(x-3\right)+4C=(x+1)(x−3)+4,问多项式AAA、BBB、CCC是否有公因式?若有,求出其公因式；若没有,请说明理由.知识点：公因式章节：数与式 / 因式分解
