When -2 ≤ A ≤ 0, A 2 ≤ Z ≤ 4.
So there is no solution;
When 0
So1/2 ≤ A ≤ 2;
When 2
so 2 < a≤3;
So 1/2≤a≤3.
2。 There is only one solution to this equation.
Therefore, x 2-5qx+4 = (x-u) 2 = 0 must be satisfied.
So u = 2 and q = 4/5.
That is, A={x|x=2}
The complement set of A in U is {1, 3,4,5}.
3。 Because b 2-8
So b 2
-2√2 & lt; b & lt2√2。