若a,x属于R,集合A={2,4,x^2减5x+9},B={3,x^2+ax+a},C={x^2+(a+1)x减3,1}

若a,x属于R,集合A={2,4,x^2减5x+9},B={3,x^2+ax+a},C={x^2+(a+1)x减3,1}求(1)使A={2,3,4}的x的值 (2)使...若a,x属于R,集合A={2,4,x^2减5x+9},B={3,x^2+ax+a},C={x^2+(a+1)x减3,1}求(1)使A={2,3,4}的x的值 (2)使B=C的a,x的值 急