T?t C?Th? D?c L?p tenth? D?c L?p 11Th? D?c L?p twelfth? D?c L?p 6Th? D?c L?p 7Th? D?c L?p 8Th? D?c L?p 9(commence array l A subset B Leftrightarrow forall x inside of a Rightarrow x in BA notsubset B Leftrightarrow exists x inside of a Rightarrow x notin Bconclusion array )b) Vi?t ph??ng trình d?a vào d? ki?n “N?u x?p m?i gh? 4 h?c sinh thì th