(1) When A crosses B=B, we can know that the elements in B set are less than or equal to those in A set ... Situation discussion:
When B is an empty set, it is satisfied that A crosses B=B, and then △ < 0, that is, [2 (a+1)] 2-4 (a 2-1) = 8a+8.
When b has only one element, △=0, a=- 1 can be obtained, and the expression of b becomes X 2 = 0, that is, B = {0 }；;
When b has two elements, that is, when B={0, -4}, △ >; 0, get a>- 1,
According to the relationship between roots and coefficients, we can get that the solutions of 0+(-4)=-2(a+ 1), 0x (-4) = a 2-1and a= 1 are consistent.
To sum up, the value of a satisfying a = b is a.
(2) According to the combination of A and B=B, B has at least two elements, and the expression of B is a quadratic equation, so there are only two elements at most. Combined with the conclusion that B has two elements in (1), the value of A is 1.
Answer over!