High school mathematics set function

(1)f(x) is a linear function: for example, f(x)=2x+4.

Then the inequality f (x) in the set b >; 0 can be written as 2x+4 >; 0, and the solution is: x & gt-2.

So far, we know that there is exactly one element in set A, that is, -3 is not an element in set B, which satisfies the meaning of the problem.

(2)f(x) is a quadratic function: for example, f(x)=-(x+4)(x-3).

Then the inequality f (x) in the set b >; 0 can be written as: -(x+4)(x-3)>0, that is, (x+4) (x-3).

So far, we know that there is exactly one element in set A, that is, 7 is not an element in set B, which satisfies the meaning of the problem.