[(AB)ˉ∪C)(AC)ˉ]ˉ
=[(AB)ˉ∪C) ∩ (AC)ˉ]ˉ
=(A∩B)ˉ∪C)ˉ ∪ (A∩C)
=(A∩B∩Cˉ) ∪ (A∩C)
=[(A∩Cˉ)∩B] ∪ (A∩C)
=[(A∩Cˉ)∪(A∩C)] ∩ [B∪(A∩C)]
=A ∩ [B∪(A∩C)]
=(A∩B) ∪ A∩(A∩C)
=(A∩B) ∪ (A∩C)
=A∩(B∪C)
建议可以先画画韦恩图
有不懂欢迎追问