题目下列多项式,能用公式法分解因式的有（ ）个.①3x2+3y23x^{2}+3y^{2}3x2+3y2②−x2+y2-x^{2}+y^{2}−x2+y2③−x2−y2-x^{2}-y^{2}−x2−y2④x2+xy+y2x^{2}+xy+y^{2}x2+xy+y2⑤x2+2xy−y2x^{2}+2xy-y^{2}x2+2xy−y2⑥−x2+4xy−4y2-x^{2}+4xy-4y^{2}−x2+4xy−4y2A.222B.333C.444D.555知识点：运用公式法章节：数与式 / 因式分解
