You could just put 0 for a and b.
It would work.
 
        
             
        
        
        
The set is not closed
Example 
-4 * -2 = 8
8 is not a negative integer
 
        
             
        
        
        
7/2h-3/2step-by-step
explicacion: 7/2h-3=37/2h5h
1/2= 3/2Expression made:37/2h 3/2 
 
        
             
        
        
        
Answer: 67 
Step-by-step explanation:
3x^2 + 5x + 25
x = 3
3(3)^2 + 5(3) + 25 
3^2 = 9
3(9) + 5(3) + 25
3 * 9 = 27
27 + 5(3) + 25
5 * 3 = 15
27 + 15 + 25 
27 + 15 = 42
42 + 25 = 67